Payment processors that handle adult material exist but they charge a premium rate. These companies could switch to CCBill as quick as they could code it up. Exactly the same as what OnlyFans did. They would have to explain to their entire customer base across the board why they have to charge more though.
Also, look at https://www.collectiveshout.org/open-letter-to-payment-proce...
They absolutely targeted paysafe and paypall. Paypall was the very first on their list, I wonder why that is. They knew the processor is the weak link.
After 10 years in the POS industry, I can assure you it came from their processor. The only card network I have ever seen take action like this is AMEX and they have have separate processing. Processors involve themselves in their customers' business constantly for risk assessment. Collective action like this is enough to make them ask, "Should we treat this as a video game vendor or as adult industry?" It's that simple to tip the scale.
Also, it doesn't make sense that Itch did it themselves. Why would they throw their vendors under the bus instead of just pulling the titles? Or are we supposed to believe they facilitated collective shout just to pull a couple of low value titles? I can't see any angle here that doesn't border on conspiracy.