Sorry for posting. I think I figured it out.
I had revision approval checked under admin > wiki > flagged revisions, but no revision approval categories selected. I still get a bit confused by the multi-select in the list box instead of it being checkboxes. I thought that list was telling me those were the categories it applied to, not to select from that list. My mistake.
For anyone curious, I also made a new category called "Unsorted" and made it so all wiki pages automatically get assigned to it. Then set that as a flagged revision category as well. I guess it's possible that people uncheck that category while not selecting a different one, but I think it's a low likely hood of occurrence and can just be handled with a little user training.
I also turned on allowing users to admin their own pages, but I'm not sure if that has any bearing on the above.