It's not how it works because, despite the money some of these creators generate, in most everywhere other than Japan traditional companies shy away from making adult themed games period, and games with any sort of kink or fetish especially subjects as taboo as potential incest in particular.
Of course there are other legal reasons as well.
So despite the pretty widespread global popularity of adult visual novels and games, until such a time as you see a significant cultural change in the West, these games are mostly going to be the purview of individuals or small teams who make money through patreon... which, as everyone should be able to tell by now, heavily incentivizes developers with just a little bit of success to drag out production of games for as long as possible to keep the cash flow as constant as possible.
I would love to live in a world where I could just count on purchasing the finished products like one can with most other PC games... though Steam's 'early access' has changed this calculous to for a lot of independent game studios.
