I don’t think review per se would be such a problem: just charge a per-upload review fee. That might weed out some of the creators who are not yet making any money and can’t/won’t invest in the effort, but is that really a bad thing for the platform?

I think the hard part is the hand-wavy stuff you’re supposed to be looking for. How are you supposed to know whether some unusual sexual act violates their standards? Or whether gay porn is legal in all applicable jurisdictions for instance?