I would absolutely disagree that they gained populaity out of pure talent.
Really, the only talented musician in that band was Grohl, people praise Cobain's songwriting skills, and I really dont think he is that great of a songwriter. They made it big because the Mainstream was tired of overproduced, overplayed arena rock. They wanted something new. It wasn't talent that got them to the top, it was Cobains determination to get his music heard. People heard it, and liked it simply because it was refreshing. They definitly didn't make it big on pure talent.