Then how do other processors go over the Visa and MC rails for these transaction types? How does Stripe allow some and then block others?

There are many bank and bank-adjacent companies who contractually enforce morals standards. It doesn't matter if the underlying reason for the morality is profit maximization, the effect is the same.

You seem to care more about the aesthetics of the sentence than the meaning behind it. We know that a company is not a person. It doesn't have a consciousness. It doesn't have a singular morality to work with. It borrows the decision making of its employees and contractors. We know that the "morality" of a bank or credit card company is really just a layer of abstraction for a group of decisions it makes to avoid bad press/sentiment/oversight/regulation. But if you analyze why people have morality, it's not that different; there are LOTS of things people would do that they currently don't if there was no underlying consequence.

It's not about morals, it's about regulatory heat and risk. Cannabis in the US remains illegal on the federal level, and the chargeback rates on adult services are through the roof.

It's pretty easy, you get hit with a surcharge on your other transaction volume if you allow something that V/MC don't want you to allow, and if you keep doing it you could get cut off which effectively makes you irrelevant to many of your customers.

As others have said, it's about perceived brand risk (V/MC allowed X terrible transaction to take place) and regulatory risk.

Or, because as you say it's money (I agree) the Stripe will put their "morals" in place - with the financial result they reduce risk, get less chargebacks and lower costs - then pass the savings on to the C-suite.

Morals, generously interpretation of the usage, was just to indicate that Stripe has a more narrow risk window.

Only an idiot would think it was about actual human-grade morals or ethics. Let alone that there were actual morality police.