They already did when it comes to Stripe.
But Stripe (middleman between itch and visa/cc) officially doesn't support using Stripe for places with adult content at all, and now they're like "if you have anything to do with adult content, we potentially don't want anything to do with you anymore".
So just not allowing payments isn't enough for them anymore, they'd ideally want itch to drop adult content entirely, even the free stuff, to not be associated with it.
Paypal isn't much better, they want as little adult content as possible in this place and officially only tolerate adult content where it's a game with gameplay first and adult content second, plus all these other content limitations.
Of course, Paypal obviously made some exceptions for Valve and Patreon, but those are making MUCH more money than itch and probably could afford special deals.