Capitalism is creating a level of censorship that exceeded what the US government was ever able to do after the Warren court. Parts of this have been there for a long time. You can drop f-bombs on cable TV all you like; the FCC can't do anything about it since it's not over public airwaves. They generally don't do that, because advertisers don't like it. Capitalism set the rule, not the government.

YouTube has put this idea into overdrive. You can't make a straightforward, monetized video about the Holocaust anymore, because the language you would have to use would violate YouTube's written and unwritten rules. Meanwhile, actual fucking Nazis have had little issue using YouTube to spread their bullshit.

Credit card companies have had issues with porn sites in terms of fraud reporting. Not necessarily because of actual fraud--if the site you use is under CCbill, it's fine--but because some guy's spouse sees the card transactions, asks what this particular line is for, and he lies and says it's probably fraud and he'll call it in. Get more than a few of those, and the processor will always be flagged for review.

They do outright stop some of the more fringe porn. Bree Mills (of Adulttime) has said that they get limited by the credit card industry far more than the government. All the faux-incest videos go out of their way to mention in dialog that everyone is a step family and over 18. You won't find scat on Kink.com, again because their payment processor won't allow it.

That's been the situation for a few decades, but it has gone beyond that in the last few years. They tried it on OnlyFans, and the company maneuvered things to show why that's an incredibly bad idea, and then the card companies backed down. But they're trying again elsewhere, and they're starting to be successful. I severely doubt they had any significant fraud issues on Steam or itch.io, NSFW items or otherwise.

Ultimately, this stuff is a tiny slice of their revenue. If they want to shut it all down on a moral crusade, they will barely notice the hit to their numbers.

On a side note, I'd like the advocate that you should pay for porn if it's within your means. You'll often find better quality stuff at sites that properly run their sets with consent. If you like queer porn or unconventional body types, there are a lot of sites for that which just don't show up on PornHub.