BTS is the textbook perfect definition of K-pop. BTS is the most popular group from Korea.
They have only Korean members, Korean management, and sing primarily in Korean. Their music and music videos are visually driven (and full of intertextuality), songs are hip-hop heavy but genre-fluid, and many are performed with fabulous, choreographed dance. These basic facts describe the core elements of contemporary idol K-pop — in fact, in some ways such as having all Korean members, they are almost more truly K-pop than some other idol groups.
The entire idea that BTS is not K-pop or trying to separate BTS from K-pop is done solely for BTS, not for the K-pop from which they emerged and which is populated with their friends and colleagues. Is the label K-pop acceptable to BTS-pop advocates when talking about TXT, Seventeen, Gfriend, and others released by BigHit? If one believes that K-pop is a negative term, does one want to “protect” these groups from that label as well? Or only TXT because that group was designed by BigHit from the start? This industry gave birth to BTS. K-pop is the social, cultural, historical context of BTS. BTS would not exist without the K-pop industry. Are they the most popular group from Korea in the USA since the Kim Sisters? Yes, they are. (And why are we giving more credence to America than Japan or Indonesia — both countries with more BTS fans than America?) Is BTS on a different level? Yes. Are they extremely special artists? Yes. But that does not mean they are not K-pop. The things that make BTS stick out, almost all of them, are also true of other Korean artists. They’re not the same as BTS, because what makes BTS different is the combination of every aspect of those seven young men, their training, and their management. But the same thing could be said about every single group. No two people are the same; no two idol groups are the same. Fans often say “only BTS this” and “only BTS that” about song writing or social messages or coming from a small company, but there is greater diversity in the K-pop industry than many people know if they aren’t actively following other artists. Yes, there are idol groups formed in a stereotypical attempt to uncreatively replicate the success of others, but there are also idols like IU who writes the music and lyrics for entire albums and who is one of the biggest philanthropists in Asia.