The problem is that Mastercard and Visa are imposing arbitrary restrictions, which Stripe and PayPal have to follow. In turn, Stripe and PayPal impose those restrictions on Itch.

If they used cryptocurrencies, they would bypass Visa and Mastercard, as well as PayPal and Stripe, altogether.

Furthermore, the current situation shows the risk of relying on payment processors. Having alternative ones is better, but it doesn't necessarily remove the risk, especially if they need to cooperate in some way.