I don't think that's a solution long term since payment processors already gone for the biggest players that distributed NSFW games, Steam and Itch are just ones they went the last for and they will go for more. Calling quits is no solution, there needs something to be done so those companies can't just pressure game hosting sites to comply to their demands.
Viewing post in bye itchio
Totally get that feeling, that kind of issue feels like something way bigger than any single person could handle. If you are UK or US citizen, there have been some legal petitions that you could sign (gotta try what is available). If you are in Europe, you can be interested in making EU Initative if you are willing to actually try to meddle with actually passing a law and represent something bigger. Otherwise just make other people more aware of the issue, spread it around so people will care. The more know, the better.
I know it's not much, but here's some petitions to sign:
Tell MasterCard, Visa & Activist Groups: Stop Controlling What We Can Watch, Read, or Play https://chng.it/b2pMbsLvdg
Mastercard: Sex work is work. End your unjust policy https://action.aclu.org/petition/mastercard-sex-work-work-end-your-unjust-policy