I've seen this type of comment a lot and I think it's worth mentioning why so many mobile apps have this rule in particular; it's the Apple store, very specifically.
The Apple store is very, very punishing to apps with any kind of adult content, and are notoriously hard to work with for indie devs (like myself) or anyone trying to get content into the App store.
Remember when Tumblr used to have porn, and now doesn't? It was because of the Apple store. The very same exact thing happened with Tapas.
If you want to hate someone, hate Apple in general. I encourage anyone who is into indie comics/games to NOT use any of their products, no iPhone, no MACs, nothing like that. They are just making it harder and harder for indie creators, especially those of us who like it horny, to make content.
Hope this helps clear things up!