Earlier quoted context omitted.
My understanding is that it's not just the processor, but Visa/Mastercard themselves have rules against certain types of merchants/products... they really have a monopoly on credit cards in general so you have to play by their rules.
You're right, but it's slightly more complicated than that. My understanding is that payment processors are obligated to follow the policies of Visa/MasterCard, AmEx, and Discover, but that those parties' policies don't explicitly ban these specific things for sale. Instead, they "strongly encourage" processors to ban them in their user agreements under the implicit threat of their risk level being increased, which i…
Some of how to interpret that is left up to the processor, but it is broadly under MCs and to a lesser extent Visa's control.