wtf ? we hunt down all Amiga demo material that was released at any time, that includes "old 90s" stuff, indeed. Kestra aims to be a repository, so ..
Anyway, at AMP, we certainly try to be up to date and as Daxb said, most MOD releases we know about come from parties. And I'm a little late there ... but the main part of the uploads are about these "old 90s", as you say.
I would look at demozoo. They gather everything that gets released almost live. Though, you'll have to filter the MOD part, I guess.