Mutiny
I don't know why they simply don't do a "two tier" payment system.
Like, if you are a casual consumer who isn't interested in the most hardcore stuff anyway, get yourself a basic subscription and pay with your credit card, all easy and simple.
And if you are a perv who is really interested in that super hardcore stuff just pay for it (on top?) with either crypto or pre-sold gift cards or whatever, even in a second sub or by pay-per-scene. Regular uses can't see or access this content.
I don't think credit card companies have any leverage against stuff that is hidden by a paywall that isn't connected with their own services. Their rules only apply to goods when using their services for the purchase of that specific good.