The payment processors don't object to you. They usually object to the store or the platform you're getting things from.
It's invisible, insidious censorship. They don't hit your hands with a ruler and say "stop, no buying that, bad". They make it so that what they don't like doesn't get to be on the store shelves in the first place. Hard to buy what isn't being sold, isn't it?
As for why they do it - it's unclear, but there's speculation that payment processor leadership might be in part ideologically captured by the usual "think of the children" moralizers and puritans. The same types that used to spurn moral panics, rally against D&D and later GTA, and are the first in line to propose sacrificing freedoms for imaginary safety - now allowed to wield covert influence over most of the payments that happen online.
If you mean Visa's porn jihad, that's most likely a saudi dude threatening to pull a large investment, it obviously has nothing to do with children, but any haram.
The usual given reason is that porn/adult stuff tends to generate a relatively large number of chargebacks, due to factors like (1) predatory/dark patterns by porn providers (2) guys’ partners seeing porn charges on the credit card statement and freaking out, and guys claiming they were “hacked” or whatever and then following through and disputing the charges.
Even if the absolute number of chargebacks is small, in relative terms it’s still several times larger than it is for non-“adult” charges, and that kinda destroys profit margins — more support calls, more work, etc.
Or so they say.
I’m not in the industry, so I don’t know. I can certainly believe that many of the oligarchs in charge are weird shitheads with bizarro conservative views, but payment processor leadership doesn’t seem to give a fuck about morals in any other manner, so it’s also kind of weird to me that they’d pick porn and porn only (a seemingly passé target for most conservatives these days) as the one and only target of a uh, decades-long distributed lowkey conspiracy that spans multiple generations of payment processor leadership. ¯\_(ツ)_/¯
Absolutely agree 100%. Even if they’re not trying to be puritans, this is absolutely the outcome.