Death metal and its subgenres have very devout fans who will not hesitate to weed out posuers and are of the few genre's that are actually objective to their own music and very critical.I can't say the same for punk,grunge,alternative e.c.t.Too much tolerance in those genre's for posuers and crappy bands/music that are encouraged to continue(to suck).
oooopps...got off topic a bit.
So how did Cobain influence metal again?
Try once,fail twice...