I'll even argue its superiority to rap/hip-hop. Both genres often have violent/malavolent lyrics, but because metal is focused on the music and rap is focused on the lyrics, those listening to rap are more prone to be influenced by the lyrics.
They'll believe it too, because they see me having a good life and being a model citizen, yet a metalhead. And then they see my sister, whose life nearly drowned in a cesspool of hedonism, a fan of rap/hip-hop.
I think the causal relationship you're implying exists here is very debatable.