LOL dumb post = pot, meet kettle. Just because you don't deal in crypto doesn't mean everyone doesn't. You do know the illegal things on the Tor network (aka dark web) only take cash or crypto right? Multiple-billions of $ worth every year. And non-KYC exchanges are still a thing for that (converts crypto to cash and vice-versa anonymously through the mail). Backed.By is simillar to SS, but only takes and pays in crypto. Dunno about the rest of the world but 50M+ Americans own it (some for investment, some for spending) and that's only going up. Why do you think Congress is in a rush to try to regulate it? As far as mail, stamps and envelopes still exist even in 2024, so unlike pay phones that have mostly gone away someone is still using those.
In a way I agree with you.
It's kind of a paradox to make something that is bound to be highly controversial and then expect the big payment processors to allow it. Everybody knows that the big payment processors have become quite puritanical about certain topics. So if you want to play with fire then don't complain if you get burned.
However it is also clear that for a lot of potential supporters adding such additional obstacles is too much for various reasons. Sadly, games which are only on SS and not on Patreon seem to be done financially worse. And it's not like it's easy anymore to make adult game development into a profession which gives a decent monthly income.
With regards to the cash in the mail method, several people are sceptical but I would probably sooner stick a $20 bill in an envelope and mail it anonymously to a dev which I like, than to pay by credit card for content which might well be actually illegal where I live, because credit card payment are very easy to trace.