It’s not related to Trump/Congress. They almost unironically got OnlyFans to ban sexual content from their own website a few years back due to the militant actions of one fringe puritanical group. They got memed so hard they eventually backed down, but MasterCard&Visa have been acting as World Sexuality Police for a very long time.

I don’t think it’s a rational financial decision, AFAICT they just have a puritanical leadership. As a cartel they don’t have to be maximally financially efficient. Their continued existence is an artefact of the 20th century, and their corporate values reflect that.

Hopefully Wero takes off soon to introduce some competition in the online payment market.