It sure would be nice if there were an off-GitHub way to help you guys with your docs. Before this new revamp, I spotted a link whose redirect had disappeared. I resorted to emailing someone on staff, and they filed an issue about it, but it was an experience that's pretty far removed from the efficiency of a wiki.
Forking a github repository to edit one file and submit it back as a PR is super-duper easy these days. You can do it entirely from the UI by just clicking the pencil icon when viewing the file you want to edit.
I'd argue the only real difference from a classic Wiki is that you need to submit the change for review. There's really no practical way we could eliminate the need for review.