Steam has started banning games that violate certain rules set forth by payment processors and other entities. This includes banks, card networks and internet providers.

As always, two things can be true gross: a lot of content on Steam is fucking awful, and payment processors acting as judge, jury, and executioner of what people are functionally allowed to buy is fucking awful. It's doubly awful when they care a lot about sex, and not at all about stuff like, I don't know, Nazis.