Genres as a whole should go away. They’re always silly. They serve mostly to argue about who’s in what genre. It’s just music. Or books. Or movies.
It has a lot to do with all music now being equally available and accessible with the same minimal effort. Until fairly recently, if you wanted to hear a musical recording from the moderately distant past, you had to work a little harder. It was less likely to be on the radio, less likely to be in the stacks at the record store. To a 22 year old, hearing John Coltrane and hearing the highest streaming song is the same thing. Everything “old” is equally old.