In an age when the charts have become an algorithmic spaghetti of streaming plays, radio and downloads, the purest way of measuring who is up and who is down in pop might be the Billboard Social 50, a sub-chart that measures reach across social networks.

At last Sunday’s Billboard music awards, its output was reflected in the category of top social artist. This included four of global pop’s usual suspects: Justin Bieber, Selena Gomez, Ariana Grande and Shawn Mendes. The winner, though, was none of the above. Instead, it was the group who have topped the Social 50 for 31 weeks in the past year: BTS.

Yes, BTS, everyone’s favourite seven-boy Korean pop act. Yes, BTS, the most-retweeted artist on Twitter in 2016, with 6 million followers, 4 million YouTube subscribers and 4 million fans on Facebook. As Kim Nam-joon (AKA Rap Monster) took to the stage to collect their award, the BTS fans, known as the Army (“adorable representative MCs for youth”), proved their point by tweeting the hashtag #BTSBBMAS more than 300m times.

BTS’s award reflects the increasingly outward-bound cultural power of South Korea. Their 2016 album Wings had the highest first-month sales in Korean history. In the US, it hit No 26, the best position ever for a K-pop album.

The pop industry is a tightly controlled big-money game in South Korea. But BTS, which translates as Bulletproof Boy Scouts, and who are also known as Bangtan Boys, were the accidental product of a smaller independent record label, who spotted a market for a slightly more thoughtful tone within the exhaustingly energetic world of K-pop: the band have included songs about loneliness and gender politics. Their label was the first to embrace the messy, unvarnished nature of social media, allowing the band to reveal more of their real personalities. Plus, rather than taking the One Direction approach of having accounts for each member, BTS run only one group account on each platform, giving them cyclonic power with which to dominate the web.

With seven members, they are petite in K-pop terms. Their rivals EXO started out with 12 members, split into two sub-groups. Their other rivals, the girlband Twice, have nine members. Both appeared higher on Forbes’ Korea Power Celebrity list this year, but BTS’s Army has allowed them to break borders.

The band also have looks on their side. At the Billboard music awards, band member Kim Seok-jin went viral as “third one from the left” when he was spotted in a red carpet photo by non K-pop fans. This was two years after he became “car door guy” at an Asian awards show simply for looking really good while getting out of a car.

BTS have expanded their reach via two Japanese-language albums, but perhaps it is a sign of the rising Asian century that they are not setting their sights on Hollywood. While they have sold out arena shows in Chicago, Illinois, Newark, New Jersey, and Anaheim, California, this year, BTS have no plans to release any English-language output.

• This article was amended on 26 May 2017. An earlier version said EXO had 12 members, this has been changed to say EXO started with 12 members.