Black Sabbath only barely registers as metal anymore to me. Ozzy's solo stuff too, Crazy Train was a bit hit so I guess they want to recognise it, but the album isn't that great.
I'm not much of a metal guy so plenty of these I've never listened to, but I was surprised by a sizeable amount of stuff I had never even heard of.
Hey they put Soungarden on here. I didn't think they would count stuff that normally gets categorised as grunge. Alice in Chains too. Definitely deserves to be there.
Good pick with Angel Dust. That should be way higher, but at least it's there.
Pyromania? F*ckin' LOL. Pretend all you want but that's a pop album guys.