Patreon does have an adult content system, though. It depends on the type of content. If you want to do a only fans like system, it's completely allowed(by both Paypal, Patreon, MasterCard and Visa).
It should be allowed, but yet it is not. Have you read Paypal's TOS? You need explicit permission from Paypal prior to setting up your Patreon. Payoneer outright does not allow adult content at all.
There are lots of adult content creators on Patreon, and most of them are breaking Paypal's rules and everyone is breaking Payoneers rules. We see evidence of Paypal waking up and cracking down on adult content creators, regardless of the content.