So have you ever asked someone what kind of music they like? 50% of the time I'm sure you hear the old "I listen to everything" reply. Oh that's great so our we might have some musical taste in common!
Wrong. So you ask them "you like Death? Carcass? In Flames? Entombed? Bolt Thrower?". If they don't outright look at you like you're some kind of freak you end up getting asked who the hell these bands are.
Don't get me wrong, I don't expect someone to know some abstract unheard of kvlt one man black metal band who released a demo from his garage cause that's what fits the BM ethos. These are some of the more well known bands in the genre that most people who aren't living under a rock have heard of.
So what does one usually mean when they say they listen to "everything"? Anything top 40. "Oh yeah I listen to rock and hip hop and pop, you know everything!". Not really. I bet its very rare you find someone who actually has eclectic taste enough that metal is part of their usual listening.
Psh people and their mainstream music ;)