Metallica because they basically stopped playing real metal and turned into radio-friendly, poppy, mainstream-friendly hard rock and everyone jumped on that bandwagon, assuming they were becoming metal fans. Then a bunch of even worse nu-metal bands sprang up and it just got out of hand for a while.
I'm just thankful that the worst we have now is metalcore. I can stomach a lot of that...but bands like korn can scrub my balls.
Do you think nu-metal happened because of Metallica?
No band ruined metal because half the bands people think of that are bad only say they are metal so in theory just the people going around saying this band that band are just deepening the wound by what is essentially agreeing they are metal, and everyone who isn't blaming those bands are just blaming bands they don't like...