There's nothing intrinsically non-primary in the format. At the end of the day they're collaborative writing projects, split into pages with internal and external links; it's just that the biggest one out there happens to be tertiary.
And I believe that they could help a lot with this issue if people migrated/copied meaningful info from forums (like Lemmy) to wikis. Forums are good for discussion, but they tend to accumulate a lot of trash; having the good content sieved and sorted in a wiki makes it more accessible for everyone.