The following is adapted from YouTuber Patrick Willems ’ new video essay “ The Limitations of the Marvel Cinematic Universe - Part 2 .” Watch the full video above.

The major innovation of the Marvel Cinematic Universe was the transposition of serialized comic book storytelling onto feature films: multiple ongoing stories existing in the same world, sometimes overlapping and intersecting. But what does “comic book storytelling” actually mean in the 21st century?

Marvel publishes dozens of ongoing series every month, each dedicated to all the characters or teams with which we’re familiar: Captain America, Iron Man, Spider-Man, Avengers, the Fantastic Four, Daredevil, Captain Marvel, et al. For decades, these series have gotten a new issue every month, and probably will for decades to come. Regardless of what’s happening in various corners of the Marvel Universe, the stories about these characters carry on.

Every year or so, Marvel stages a big crossover event like Civil War, which divided Marvel’s heroes in an ideological battle; Secret Invasion, about Earth being invaded by an army of shape-shifting Skrulls; or House of M, in which Scarlet Witch’s mental breakdown created an alternate reality. These stories always end in a way that changes the universe and sets up a new status quo (or as Marvel puts it, “Nothing will ever be the same!”). This new status quo is then explored in the various ongoing series for the next year. At the end of Civil War, a brainwashed Sharon Carter assassinated Steve Rogers, and the series explored the fallout: Bucky, aka the Winter Soldier, took over the mantle of Captain America, and Tony Stark became the director of SHIELD and put together a new team of government-sponsored Avengers.

This status quo remained consistent for two years, until the end of Secret Invasion. There, Norman Osborn saved the world and replaced Tony Stark as the head of SHIELD, creating a new Avengers team composed largely of villains. For the next year, Osborn imposed his will upon the world as the heroes tried to stop him. Iron Man’s solo series followed Tony Stark going on the run to prevent Osborn from extracting technological secrets from his brain. Comics are fun.

This is exactly what Stan Lee meant 40 years earlier when he insisted Marvel’s comics maintain “the illusion of change.” Sure, Steve Rogers returns from the dead and becomes Captain America again. Norman Osborn is eventually taken down and sent to prison. But these changes in the status quo stick around long enough that we get years’ worth of stories dealing with them. We spend time with the characters reacting and adapting to the consequences of the big events.

The nature of feature films doesn’t allow for ongoing series to follow individual characters. The arc of Marvel’s solo movie trilogies, like Captain America or Thor, tends to be an origin story followed by a self-contained adventure culminating in a crossover with other characters. We’re not getting monthly or even annual Captain America adventures.

these are massive changes in the lives of the characters, but they don’t have the weight they’re intended to have

Here’s why that matters: After Phase One, each of the big MCU movies ends with a seemingly new status quo. In Captain America: The Winter Soldier, SHIELD collapses and Hydra returns. At the end of Avengers: Age of Ultron, there’s a new Avengers lineup. At the end of Captain America: Civil War, the Avengers split up.

These movies are the equivalent of the big crossover events from the comics, without any of the fallout or impact witnessed from the individual perspective. We don’t really feel the changes in status quo, making the illusion of change more difficult to spin. (And with Agents of SHIELD so far removed from the actual action, the serialized companion doesn’t bolster the impact.)

SHIELD shutting down in The Winter Soldier has no effect on future stories; one movie later, Nick Fury shows up with a SHIELD helicarrier, as if nothing ever happened. Captain America is still doing the same kind of missions, but his costume now has an Avengers logo on it. The remains of Hydra are dispatched in the opening scene of Age of Ultron ... then, basically, we see a few Hydra operatives in one scene in Ant-Man. The new Avengers lineup gets to do one mission at the start of Civil War ... and then the Avengers disband. On paper, these are massive changes in the lives of the characters, but without the stories exploring them, they don’t have the weight they’re intended to have.

After Civil War, the next story featuring those characters is Avengers: Infinity War, the biggest of all crossover events. The characters make some brief, vague references to what happened to them between movies, but there’s no time to show or explain it. Captain America is just a supporting character in Infinity War. He shows up, he fights, he says hi to some friends, and that’s it.

Comics open doors for readers who crave character foundation. You can pick up Iron Man’s solo series to get in his head and understand the new status quo from his perspective. But the business of the MCU means Tony Stark’s stand-alone story ends with Iron Man 3. To follow the hero, you have to see the Captain America movies, the Avengers movies, and even the Spider-Man movie. And since he’s no longer the lead character, major developments in his life either happen off-screen or in movies where he’s a supporting character. He and Pepper Potts break up, get back together, and get engaged between movies. In order to serve the ongoing MCU, the films have to skip over years of characters’ lives and reduce them to supporting roles.

No character embodies this more than James Buchanan Barnes, aka Bucky, aka the Winter Soldier, aka ... the White Wolf? Bucky has appeared in four Marvel movies, and changed more than any other character. He was a young soldier from Brooklyn in World War II; he was a brainwashed Hydra assassin; now he’s a haunted recluse trying to piece his mind back together. Also, he lost an arm. But how well do we really know Bucky?

What the MCU is missing is best explained by a closer look at Ed Brubaker’s Captain America run from the mid-2000s, which reintroduced Bucky as the Winter Soldier. Like in the movies, he ran into Steve Rogers a few times before Cap learned the truth about his identity. The twist: After handling the Cosmic Cube, known to MCU-only fans as the Tesseract, all of Bucky’s memories are restored. He freaks out, overwhelmed by guilt for all the terrible shit he’s done, and over the next few stories he starts figuring out what to do with himself. He helps Cap stop a terrorist attack. He begs Nick Fury for a job at SHIELD. Then, when Steve is assassinated, Bucky ends up taking over the mantle of Captain America.

Once his memories were restored, Bucky basically got his own story. He dealt with what happened to him, made choices, and grew. By the time he put on the suit and picked up the shield, he was a fully formed character that we understood and cared about.

Captain America: The First Avenger establishes Bucky with 20 minutes of screen time — and then he dies. He returns as the Winter Soldier, where we learn his identity about an hour and a half into the movie. The film ends with the image of Bucky learning about his past at a museum. That’s a great setup for him to have a journey of self-discovery, reconciling with his past deeds. But there isn’t room in the MCU release schedule for that story.

Bucky next appears two years later in Civil War. He’s living in Bucharest, and as we learn later, he’s already pieced his memories back together. But we don’t see that story, because as soon as Bucky shows up, he’s already been framed for a terrorist attack. This is a movie that entirely revolves around Bucky; whether it’s people chasing him, protecting him, brainwashing him, or fighting him, he’s at the center of the action, but without much of a foundation. There’s only one reason to care about him: because Captain America cares about him. Bucky is a human MacGuffin.

The serialized storytelling that Marvel Studios, Kevin Feige, and their armies of filmmakers have accomplished is astounding and unprecedented. For the core characters and arcs, it mostly works. There is an enjoyable ongoing story and consistent continuity through nearly two dozen movies over more than 10 years.

But the drawbacks of the system are starting to show. What Marvel’s essentially doing is cramming a square peg (serialized interconnected comic book storytelling) into a round hole (feature films). It’s easy enough for Bucky to step up and become Captain America in the comics when the creative teams have the time to build up his character and get readers invested in him. But if the MCU intends to do something similar — since Avengers: Endgame looks to be Steve Rogers’ last film — then the folks at Marvel have a challenge ahead of them.

A solution may have already presented itself with Marvel’s upcoming Disney Plus shows. Unlike the various Marvel series on Netflix or Hulu, these shows will actually tie directly into the films, with one series rumored to focus on Bucky and the Falcon. And since comic book storytelling has a lot more in common with episodic television than feature films, this might finally be the opportunity to spend some time developing these characters away from giant battles for the fate of the Earth.