So yeah, being mad at Valve is stupid, people need to be mad st MC and Visa and probably also PayPal.
Being mad at Valve is shooting the messenger.
Fortunately the petition is at least correctly aimed at the payment processors.
But also...
If MC and Visa won't budge on their positions, well, if Valve then makes an alt payment system for adult only games...
MC and Visa go, oh, hey, you're violating our guidelines, we no longer support Valve/Steam, now no one can buy any game.
This is a MAD situation, Valve would have to come up with a comprehensive payment processing system for everything, in secret, and then deploy it all at once.
It is, actually, allow me to explain:
Visa and MasterCard have policies for who they do business with, ie, merchants and vendors.
The business they do with Valve is the business of processing online payments, Valve is one of their merchant partners.
They can absolutely shut everything down in the name of upholding their own moral / business standards, via deciding to no longer be a business partner with Valve.
If Valve uses an alt payment system for adult games, Visa and MC are still business partners with Valve, Valve is now in violation of their partnership guidelines, ergo, Visa and MC drop Valve.
Visa and MC are concerned with the reputations of the partners they have, in general, not so much with the exact transactions they actually process.
No, its not, and Valve did have to act in this way, see above.
Itch.io and Nutaku just did the same thing after Valve did, you can no longer buy any games that cost money, that have explicit sexual content, so by your logic, its Valve and Itch.io and Nutaku all being unnecessarily censorious, of their own accord, rather than the reality, which is that MC and Visa are strong arming all these digital market places.
EDIT: In itch.io's case, they even delisted their totally free adult games.