True, but also—itch.io has failed to do even the smallest hint of protest over this. There is nothing to suggesting they aren't going along with this willingly.
They could have published their letter from VISA/MasterCard. They didn't. They could have put a big protest banner on the front page. They didn't. They could have spoken out about payment processors acting as de-facto global censorship. They didn't.
In fact, the wording in their https://itch.io/updates/update-on-nsfw-content goes out of it way to downplay it, with corporate passive language like:
prioritize our relationship with our payment partners and take immediate steps towards compliance.
also note that, when they talk about that they skim the site for games to remove, they talk about the removal by an extremely stealthy litotes:
We are currently conducting a comprehensive audit of content to ensure we can meet the requirements of our payment processors.
Of course, this is so cleverly hidden that they have to later point out what they're actually saying:
Part of this review will see some pages being permanently removed from itch.io.
(but note the use passive voice, avoiding saying who will perform said removal, namely themselves)
I think this sites blatant compliance should be criticized, too.