Hi! this is a interesting topic so thanks for creating a discussion for it.
i have to say, and i'm sorry if this offend anyone that uses the term but i cringe so hard every time someone says btspop.
To me this whole is BTS kpop? debate comes from our bad habit of putting people or things on very narrow boxes full of prejudgements and refusing to see anything that is out of those boxes. BTS debuted as a k-pop group, still promote as a k-pop group and most important have no problem with the k-pop label. If you have listen to their older song you'd understand that coming to terms with the "idol" label was not easy to some of them so now that they're finally at peace with it i find it so upsetting that fans decide to ignore that part of their journey as musicians and say they're not k-pop. Because they're not even doing it to benefit the group, it's just for their own ego.
To me BTS is a perfect bringe between kpop and the "artist music", they don't have 100% fit in any of those categories because those categories are very narrow minded anyways. BTS has said since day one that their objective was to fight against prejudice and i think that been a k-pop group that defy all those stereotypes people have about "idol music" is a perfect way to do it.