In an increasingly self-aware culture that’s rooting for equality, it’s tempting to point fingers at music festivals for a lack of diversity across the board. As usual, when Boston Calling announced this year’s lineup, it was hard to find much of anything to gripe about. There’s genre diversity with rap, folk, rock, and electronic artists spanning the three-day festival. There’s racial diversity that doesn’t depend on rap acts to represent black musicians entirely. There’s gender diversity with a little less than half of the acts including a female-identifying member. But as anyone can point out, most of that diversity is filtered to the bottom of Boston Calling’s lineup.

The festival’s sole female semi-headliner is Paramore, a pop punk-turned-tropical rock band, thanks to lead singer Hayley Williams. Friday night saw the band offer up a spectacular performance from beginning to end, performing 16 songs in just over an hour. Paramore kicked off a high-energy set with “Hard Times,” the lead single off of last year’s outstanding After Laughter. Though the majority of the set was comprised of new songs, the crowd reacted intensely to it, with hordes of onlookers dancing in place or belting along if they knew the words. Older tracks like “That’s What You Get” and “Ignorance” felt deafening as the crowd screamed in unison with Williams. As tempting as it is to highlight her enigmatic and sometimes frantic dancing onstage, a mesmerizing thing to witness, the rest of the band upheld their end of the show, too. Guitarist Taylor York threw himself into the instrument, at one point flinging it off during the surprising inclusion of interlude track “No Friend.” Drummer Zac Farro couldn’t have snuck in more boisterous drum fills if he tried. No, they didn’t play “Misery Business” because they didn’t need to. Paramore has an extensive musical arsenal to last them for hours. At one point, the band even stepped aside to let Farro’s side-project, HalfNoise, perform a song. Paramore’s set was defined by surprising festival risks like that and their nonstop energy. Calling their set fun would be a ridiculous understatement.

When Paramore’s set ended, the crowd remained in place, cheering for an encore, even 10 minutes after the band left the stage. Fans clung to the metal barricade until long after the crew began breaking down stage equipment. Strangers turned to one another and shared a communal exuberance about the set they just witnessed. This happens after festival sets sometimes, but the degree to which it did after Paramore was different. There was a proper sense of fanfare and afterglow. This wasn’t just a few dedicated fans. It was a sizable portion of the crowd, many of whom seemed to be there solely to see Paramore.

So why didn’t Paramore headline? For the opening night of a three-day music festival, their set offered everything you could want while also going beyond expectations. Check Twitter and you will find dozens of messages of excitement prefaced the performance. People flew in from Europe, Canada, and Australia to attend their festival set. It’s what a festival headliner should prompt: “Oh my god, [artist] is playing. I have to go.”

Let’s look at who did headline on Friday night: The Killers. Finding those same type of extensive travel plans by fans of The Killers is hard to do because there was less of that — or, hey, maybe their fans are just a little less vocal. The alt-rock band started their set with a ballsy move, beginning with “Mr. Brightside” and then churning their way through some Hot Fuss singles and other vaguely familiar-yet-not-at-all songs. Their stage was spotted with vibrant light displays. At one point, the band shot pink confetti into the crowd. Later, they covered Tom Petty’s “American Girl” and randomly threw in titular hollers of “Free Fallin’” during the outro, each time off beat. The Killers aren’t a bad band. They have memorable hits, they play with slightly subdued gusto, and Mormon frontman Brandon Flowers has experience performing to large crowds. The difference is that when a band like The Killers plays songs that aren’t their hits, the crowd stands still. Diehard fans in the front sing along, but the rest of the crowd bailed to grab food or lay down on the grass, chatting with friends. Instead of trying to imbue their other material with the same bubbling energy tracks like “All These Things That I’ve Done” or “Smile Like You Mean It” have, The Killers just stroll forward, offering little worth talking about afterwards. They resorted to actions that felt like gimmicks, such as pulling a fan onstage to drum to “For Reasons Unknown” or letting the crowd know that the Celtics were beating the Cavs. (Note: the Celtics lost last night’s playoff game. Read into that what you will.)

There’s a lot of reasons why a band like Paramore would place second as a headliner when pitted against a band like The Killers. Maybe it’s because The Killers’ most popular song, “Mr. Brightside,” claims a more prominent nostalgia factor for non-fans than Paramore’s most popular song, “Ain’t It Fun,” does for non-fans. Maybe it’s because The Killers debut album was released on Island Records and Paramore’s debut album was self-released — an imbalance of major label funding from the get-go that changes when, where, and how songs are funneled into the ears of potential listeners. Maybe it’s because The Killers choose to perform in venues like TD Garden whereas Paramore choose to perform in cozier theaters, like the Wang. There’s too many unmeasurable factors that contribute to a band’s success beyond the numbers: advertisements, fandom, interviews, social media, streaming services, playlists, and more. There’s also a big factor called sexism, though nobody wants to own up to it. There are measurable factors, though, and those statistics paint an interesting light on the two artists.

Since their formation in 2001, The Killers have released five studio albums. All five placed on the Billboard 200 chart. According to Metacritic, a site that aggregates scores from various press outlets, every album has accumulated a grade between 64 to 71 (out of a possible 100). Their highest charting album was Wonderful Wonderful at #1 in 2017. They’ve had 11 singles place on the Billboard Hot 100 chart. Their most popular song, “Mr. Brightside,” came out in 2005 and peaked at #10 on the chart. They’ve been nominated for seven Grammy Awards and won none. The Killers have not changed their sound or style much over that period, signifying an unwillingness to take risks. They haven’t maintained an intense fandom throughout their career.

Since their formation in 2004, Paramore have released five studio albums. Four of those placed on the Billboard 200 chart. According to Metacritic, every album has accumulated a grade between 67 to 82 (out of a possible 100). Their highest charting album was Paramore at #1 in 2013. They’ve had 11 singles place on the Billboard Hot 100 chart. Their most popular song, “Ain’t It Fun,” came out in 2014 and peaked at #10. They’ve been nominated for two Grammy Awards and won one for Best Rock Song with “Ain’t It Fun.” Paramore have changed their sound and style numerous times over that period, signifying a willingness to take risks. They have maintained an intense fandom throughout their career.

Compare those statistics and you will find the two bands are pretty similar, except that Paramore has continued to improve musically according to critic consensus and popularity rankings. Based on performance alone, Paramore should have headlined the main stage. Clearly, we don’t live in an age of festivals where that will happen, but it should, and watching the two sets back to back made that evident. If you can raise intrigue in non-hit singles during your set like Paramore did with “Pool” and “Caught in the Middle,” or, even better, get people to dance along to those songs, you’re performing in a way that highlights the energy and power of your work. How do you prove you’re capable of doing this beyond videos and crowd size? More importantly, how do you prove that to bookers who pit the allure of one band against the next? There comes a point where it feels like there’s no further way a band could justify their importance, success, or fun, and in turn justify why they should headline. How do you earn that headlining spot? What metrics do you need? What do you have to prove? Better put, when will you finally be considered enough to be on the same level as your male peers? It’s a grave question familiar to many women and nonbinary folks. Unfortunately, it’s a timeless question, too.

This builds a low-hanging ceiling at the festival that exaggerates the impossibility of most middle-tier and lower-tier acts becoming future headliners. Indie power pop group Charly Bliss was an injection of pure happiness, all energy and uplifting choruses, and they have the material to become a bigger name in time if given the space. The slow-burning folk rock of Big Thief lulled listeners into a comfort zone and showed their skill for effecting lyrics, a skill that has and should continue to earn them a growing fanbase. Frontman Mike Hadreas of Perfume Genius sauntered across the stage while delivering soul-baring chamber pop, embracing both the gleeful and the difficult parts of queerdom that encourages others to do the same. Noname unfurled a string of beautiful prose about damage and growth, the kind that positions her as a soft-tempo rap figure that deserves, and could likely receive, a far later time slot. Even Pussy Riot, the Russian feminist and anti-political group, who spent their set lecturing the crowd about socioeconomic equality and international affairs through digitized forms, felt primed for a larger platform but cramped on the Blue Stage. By not making space for non-male, non-white acts on the main stage, Boston Calling makes it harder for all of these artists and more to see themselves in the same place, facing a massive crowd, given the opportunity to own the show years from now. If we don’t have inclusive headliners, why should lower-booked artists believe they could be given that spot someday in the future? At what point do we stop rewarding a band just because we rewarded them once before, especially if it means making space for someone new?

But look, Boston Calling has plenty to be proud of. In 2017, Boston Calling booked one of their most musically diverse bills. In 2016, they had two solo female headliners. In 2015, both spring and fall editions of the festival let bands with a female member headline. In 2014, they highlighted both veteran and rising musical artists. In 2013, they let local artists perform on the main stage. The festival has never been offensively bad or in the wrong; they just have room to improve. The one thing that’s consistent throughout the festival’s existence is its lack of female headliners. Over the course of all nine Boston Calling festivals and 22 headlining spots, only five artists with a female member (Sia, Robyn, Pixies, Alabama Shakes, and Lorde) have headlined. This year’s lineup sets them back significantly in that statistic. Looking around, the solution seems obvious. Or maybe female performers just need to try a little harder, you know?

Stay tuned to DigBoston.com for more coverage of Boston Calling over the course of this weekend.