One thing I think about a lot is that in a lot of artistic fields, there's often a niche for "art loved by artists". Poetry that mostly people who write poetry like. Architecture that mostly architects like. Painters that most people dislike but other painters love. And I think this is somewhat of a recent thing as well (recent as in last 100-200 years or so).

For classical music, I have a theory that instead of splitting into two, it split into three. To overly generalize, there's the mainstream classical music everybody loves to listen to, mostly game/movie/tv soundtracks. There's the classical music that fans and critics of classical music loves (the subject of the article, the avante garde, the neoclassical, etc.). And then the classical music that classical musicians like, which is mostly stuff written by the old great composers (my impression is that classical musicians aspire to play famous old pieces more than they get excited over new pieces).