Itch.io isn't the first target, before they have been many more like Steam or certain japanese sites like DLSite. Saying that itch.io should somehow be even better than Steam, that despite being thousand times larger had to also comply, is quite unfair, especially considering they are way smaller and with way less people on board (and they sure don't have system to verify games that don't comply with processors in the first place, which they now have to install). So hey, moving to another site won't solve the issue, because any site will meet the same fate unless we act and do something about those payment processors. They will always have to cater because you can't fight over someone that literally decides if you are able to earn money or not, where Visa and Mastercard responds for most transactions in the entire world. Many more NSFW creators will be treated like that if we don't do something tangible instead of complain on each service that has to comply and pray that does something.
Yes, they targeted other sites before, however
1) Itch.io's handing of "Oh, we shadowbanned everything NSFW without a moment's notice, sorry (lulz)" is just terrible and 2) Steam is bigger - but has far more "mainstream" games. Steam can easily shrug off losing the handful of NSFW games in favor of keeping the mainstream ones - Itch.io has many more smaller developers and many more NSFW games, so the stakes are different for them: NSFW content likely is a much bigger share than e.g. on Steam, so they should try to fight for that bigger piece, or at least not act in a way that will NOT burn all goodwill towards them (instead of how they did act)
Yea, they definitely should be more professional in terms of the first point and that was always a thing before albeit we don't know how it looked on their end. Maybe they got an actual legal letter and they had to act fast? Some people already have been thinking if they didn't have something serious as a bonus that made them act faster: https://bsky.app/profile/torrent-empress.bsky.social/post/3luowy64rcl2y
Worth remembering that itch.io staff is small. They didn't have ways to check if games are breaking the rules or not and it was put on the users to potentially report those. Now that itch.io has been forced to get rid of certain NSFW games and they can't check it easily, the only thing they could do to comply and not lose a major way of paying developers on the site was to nuke everything and then try to potentially hire people to actually check that stuff or try to somehow do it on their own.
Responding to second point, I don't think they wanted to lose that pie either. For them it's way more of a big deal than Steam because they have been hosting NSFW games for so long but it's really difficult do to much if your own payment processors are literally against what you host and give you an ultimatum, which they shouldn't be able to do in the first place. That is the true problem that needs to be resolved, because otherwise it will keep happening and they will start leverage their power to censor something more than just controversial porn.
Moving to another site won't solve the issue, but it will provide a deterrent to other companies doing the same.
And it will protect devs and customers from the risks involved with working with such an unreliable platform which instates blanket bans (and which removes much more than the bans, even) with no prior warning and even with the delisting of purchased titles.
Provide a deterrent? I am sorry but I cannot agree. Companies will always choose survival over going bankrupt and closing down and that's basically what happens when you can't pay people. Users moving out to other platform will just make that one be next target in the future once it gets big enough, that's buying time more than anything. If payment processors and card companies mandated what can be sold with their services before, next will fall in the line because hosting content isn't a charity. Itch.io saved their asses first like any company would do, because NSFW content ain't the only thing they have to worry about.