^Jim Carrey was apparently a huge fan.

I kinda doubt that cameo appearance alone is responsible for their popularity though.
BoneSnapDeez wrote:"Covenant" was on a major label.
Those Columbia Napalm Death and Carcass records weren't very good. And they were still way too extreme for a mainstream audience.
Don't forget about "Domination"!
To be fair to ND, those 90s albums were more the result of the band just kinda experimenting with a lot of different ideas and not really the result of them actively trying to appeal to anyone in particular.
Carcass is a different story from what I understand though. Apparently when they were working on Swansong, the label actually suggested that Walker learn to actually
sing.
The major labels basically thought they'd get the next Metallica from extreme metal. Didn't work out for them!