its relevant. even if its not, its good for musicians to know these facts.

bassix, its always been like that. pop has always been mainstream.

well think of it this way. there are 2 groups:
1.famous ppl using(misusing) music
2. musicians becoming famous

u're just looking at one side of mainstream music. come to think of it, in these days u can even call many bands like metallica, acdc mainstream since almost everyone listens or knows them too.