The real source of this particular evil is Visa and Mastercard; both of whom strictly do NOT want their services and brand "associated" with sex. (Which is why every porn site in the world uses a third party payment handler.)
The 'But why?!' is strictly business:
Visa and Mastercard both do business internationally, all around the world. Some of their business comes from places and cultures where the association of their brand with pornography would be enough to entirely see their business banned in that country. (Hi, middle east.) -->
So both credit card companies basically tolerate the third party arms-length payment providers, so long as there is plausible deniability. But as soon as that plausibility fades, they get dropped.
Business marches on, catering to the most bigoted common denominator. :\
The shitty fact of life here is that this isn't a fight creators can win. It's the financial equivalent of picking a fight with the sea:
You can strike the sea, but the sea will never notice, nor care, and it will destroy you in turn without knowing, caring, or even realizing.
So what do you do:
Plan for disruptions. Be ready at all times to jump to the next payment processor. Have multiple payment processors lined up for you to work with, and when one gets clobbered by the credit card companies, jump to the next one.
I disagree with its not worth finding a way to fight with. I knew, & do, the reasons. Ko-Fi's initial statement made it appear as if it was the Paypal that was the issue, which might be still in some way. Paypal can be swapped out for banks tho - the rest still stands.
PayPal is the issue, but PayPal is the issue only because Visa and Mastercard are leaning on PayPal in turn.
PayPal is a big fish, but Visa et all are titanic behemoths with market capitalization larger than most nations. :\
Even if PayPal wanted to, they can't.
The third party payment providers generally can be called "plausibly deniable" so long as they aren't named like, "SexCoin" or something like that. -->
That way Visa and MasterCard can pretend to be shocked and tut-tut when political interests in socially conservative regimes go: "You are profiting from pornography rabblerabble!" -->
Then Visa or Mastercard can just wash their hands with a "Oh, that's a naughty third-party provider, we'll get rid of them right away." and they lose a company that makes them 1-30 million a year and keep doing business in a country worth billions a year.
The entire stupid thing revolves around "Everyone knows Visa and Mastercard make money off of pornographic services, but as long as you can't prove it, they can keep on doing business in lucrative-but-socially-conservative places and regimes."
And ultimately, never, ever lose sight of the fact that even PayPal is a TINY fuckin' fish compared to the waters they're sharing with Visa and Mastercard. Multiple orders of magnitude difference.
PayPal can no more fight this, even if they wanted to, than we can.