I wonder why Monk is doing this.
iirc in one of his older updates he broke down the financials of the game, he basically loses money, so he's got a story to tell but it's a side project If he plans to slow down dev but "eventually finish the game", he may not want people to throw money at him on a monthly basis.That would only explain Patreon though. As far as I can find, Subscribestar has no issues with most if not any "problematic" content.
I also think the AVN market on patreon peaked awhile ago and this game doesn't get the recognition it deserves.