I have a feeling that they are trying to protect themselves from being charged with selling adult games to minors, just like Patreon won't let any games with sex between family members on their site. It's too bad, but the corporate view is always "cover your ass."
Viewing post in Paid version cancelled due to itch.io policy changes comments
I do not think this is the case. If there was any danger in that area, patreon would drop each and all adult content in a flash, as patreon is a lot more restrictive than itch in that area, like with the incest thing. It is even debateable how "adult" cartoon boobs are.
We will see in the months to come. But I have a feeling that it mostly targets accounts that have paid content with 0% revenue sharing in combination with refunds and adult content. While they claim that revenue sharing is not the deciding factor, it is an indirect factor in assessing the financial risk involved.
Or think about it, if they would want to ban certain things, they would ban it. But here they are, happily giving a free platform and allowing links to patreon, subscribestar, and all the others, and even giving opportunity to take the payment risks yourself, on their website, not needing for the devs to make their own, if they are able to get approval of paypal for direct payments (and this must be possible, because paypal does indeed allow adult content. But probably not for all countries or amateur accounts).