No, it has nothing to do with chargebacks. It's not even presented that way in their policies when they ban it. They consider it a "brand risk", which is completely different.
I also remember a story from someone I worked with in the 90s. At that time there were adverts in the back of newspapers for VHS tapes, very cheap. It would say "Get these 8 HOT VHS tapes for $4.99 inc shipping." People would call up and order on their credit card. The reality was the company would only send out a handful of these packages and then claim to be out-of-stock, then they would mail a refund check out to everyone else. The check would be from BIG TITTY BUSTY WHORES LLC or something. Literally nobody would cash the check.
There hasn't been sufficient reporting on all the lobbying and back-room dealing.
There has been tons of reporting on this in the industry. It is not hidden. The war on sex work is extremely well-documented, as is the explicit shift in tactics to targeting financial infrastructure as a tactic.