No, itch.io hasn't banned all pornographic content from their platform. They've just made it impossible for my account to sell anything. This has happened to similar developers, but not all and I believe it is still happening from time to time. The reason why those specific developers and myself were targeted has never been made clear by itch.io. The only reasoning I got from them was the following (also quoted in the news posts I made around the time it happened):
This decision was made after considering various factors related to your account, including nature of content, risk, disputes, and the resources required by our team to review payments associated with your account.
As far as I can tell my game sales weren't overly affected by refunds and or fraudulent charges. So I'm still not sure what prompted the account restrictions.