Oh, the one on RYM?
Yeah, I've read a couple of that guy's posts.
The gigantic clown.

So how did anybody find out about Primus? Inform me...

First I ever heard of them was from the Bill & Ted's Bogus Journey soundtrack.
And they seemed to be on 120 minutes almost on a weekly basis after that.

I don't understand the question. Are you operating under some kind of assumption that the only way people found out about bands in the 90s was via mainstream rock radio?

Haha, same here.

No, but I presumed bands like Primus that were signed to major labels and charted were discovered through means other than word-of-mouth and underground zines...

Primus is, to me, the classic example of a slow burn band. They never had some huge breakthrough, they just slowly got more and more well-known throughout the 90s. Urban and I both first heard of them from Biil & Ted's Bogus Journey. Other people no doubt saw one of their videos on 120 Minutes or heard about them from their friends. As the 90s wore on they got bigger and had a couple videos on daytime MTV so they became more well-known. By the second half of the 90s they had some songs that you might hear on mainstream rock radio sometimes but they were hardly the staple of it that you seem to think they were.

plus you had the whole Lollapaloza thing too.

Most of the bands on that tour got blanket coverage in the specialist music shows & magazines. It's pretty rare to find a band that didn't get over from that tour.

And I'm sure they received a fair bit of attention through their South Park theme song and Mephisto & Kevin.

You may be completely right.
What I should have said was: The 80's haven't produced (as far as a decade can produce anything) much good music for me ;).
I still think of it that way by the way. Can't think of any band I really really like that originates from the 80's