Earlier quoted context omitted.
Why should payment processors force them to. They will make less money
Some years ago I interviewed with a company that served as a payment risk processor for high-risk businesses (in short, porn). The chargeback rate on online porn is huge . As a result, where a traditional payment processor may be 1.3–3.5% depending on the business and the assessed risk, for a high-risk business, the rate can be much much higher. While Onlyfans keeps 20%, I'm guessing that they'd be badly hurt if they…
But many comments here imply that chargeback is almost as easy as clicking a button or asking nicely. How's that?