Really? So they're all just talentless people who write garbage and the only reason people buy it is because it's on TV? C'mon man...And Good girl gone bad is one of the best pop albums of the decade. :\
Ok, yes, I'm not disputing that, but this is 1997 we're talking about. Sure, it's much more likely that a band will gain success if they're promoted by a major label, but I haven't noticed The Mars Volta pushing as many units as Creed or Rihanna, even though they're all on major labels (right?). For every Creed, there are dozens of banRAB on major labels that never came close to that level of success.
So, yeah, I'd say the music plays a great part in a band's success.
I'm pretty sure every label has some criteria of the music they want to promote....:\