I don't know where you got that idea from because I can list like 15 games of the top of my head that fit under "Anime-Style hentai games" on Steam. Matter of fact, I can name 3 publishers that do just that.
Which three publishers?
You mean like Kagura? That's grey area business operation.
They take out the hentai element out of the game, then publish the game as non-hentai game on Steam.
Players then download the hentai version dlc from Kagura website.
Of course, Kagura take commissions from providing service like that.
It's very shady because Steam gives a blind eye when there are publishers doing this. Then bans indies for doing this without publisher.