I think the appropriation discourse completes misses how much these white artists did for making black culture acceptable in the white-dominated mainstream and bringing people of different races together. It would have been great if the black music that their music was based on got more commercial success, but lets not pretend that would just have happened organically in the 50s-70s if there had been no popular white artists in those genres. And it's not like black artists didn't also profit from the newfound popularity of black genres.

The beetlemania was a bit much but the beetles did pioneer new music, just look at their white album

No argument about the motives of record companies but Elvis was criticized by white people partly because, unlike most swing and country musicians, he openly praised his Black heroes and mentors. He was hated for bringing Black music to White kids. A for Nirvana, it was just the right sound+message+image at the right time.

Now, Zeppelin... I got nothing. I just want to continue loving Zeppelin.

Nirvana and The Beatles are super over rated and are only well known because they sold out/were promoted

Well... there it something to be said for breaking new ground or being innovative in your field, both of those bands were are the forefront of massive pop music waves. It never hurts to be first at something.

zeppelin stole from spirit as well, but spirit didnt really care that much (the riff for stairway to heaven is directly stolen from a spirit song)