In addition, in a black market, there is no need to follow any standards or to have any values. It's not unlikely a prohibition selects out such people. Blanket prohibitions are a very bad idea and a bad form of policy. A prohibition restricting content involving abuse (or #HumanRights #FreeSpeech
otherwise involves a sexual proliferation depicting someone's likeness w/o their (adult) consent) make sense, but more abstract and conceptual prohibitions do not (and are very problematic when it comes to #HumanRights).
For more, I have a post about various things to do with porn. #FreeSpeech