Could be wrong, but I think it's less puritanical, and more that transactions with these types of vendors are overwhelmingly fraudulent and charged-back. It's a big liability for the processors.
It could also be because, as suggested in another comment[1], banks are getting regulated in a way that the payment processors simply don't want to deal with.
This is a common reason that’s given, but I haven’t seen any proof. I wouldn’t be surprised if this is surprisingly overblown and the industry doesn’t actually have that bad a problem with charge backs
I wouldn't call it a "massive issue". If you have a reputable ecom business your rates of chargeback and fraud should be quite a bit under 1%. Adult businesses however can have triple or even greater than that.
If you can't absorb 0.5% in loss, then you shouldn't be in ecommerce. Same thing as being in bricks and mortar, if you can't absorb shoplifting you shouldn't be in business.
Not relevant in this case, but for low margin physical goods the math can be much worse. You're out the cost of the good, the taxes and fees associated, the margin, and the chargeback fee. For food delivery middlemen, for example, it's a really rough game
