Because people tend to panic and claim fraud when someone finds out about their fetishes and the porn they're paying for, since refunds cost credit card companies even more money then their refunding. So they tend to charge porn sites more in order to use their services in order to cover potentials refunds.I explain it as easily as I can: pedo stuff, that you introduced in the debate, is ILLEGAL, even the fake depictions, as far as I know (there was a debate, mind you, in my country about DRAGON BALL of all things). Or they are at least borderline and risky.
So, being illegal, I can understand everyone banning it.
The other fetishes might be strange, distasteful to some, but they are not illegal by any means (and, obviously, I'm still talking about the fake depictions).
So there is no reason to ban the other, LEGAL, depiction of fetishes. And indeed, more often than not, they seems to be not banned (I don't know what happened to pornhub particularly, still not the point).
I've read about credit card companies being burnt somehow and then, to return to my original question, I asked:
In Patreon's case they managed to get a lower charge rate in order to maintain a better revenue split with creators, in exchange patreon had to make fetishes that have a decent chance of getting panic refunds or actual laws banning them against the TOS in order to maintain the favorable contract with credit card companies and paypal.