My issue with horny RPGs is that if you can find people to play with that are into whatever kink the book is catering to, why would you bother to play at all? Just have sex.

Because the point is role playing. You might as well ask what’s the point of any kink, fetish or sexual situation that isn’t two married adults having sex for the purpose of procreation. Building up trust and eroticism is the point for a lot of people, even in plain porn¹

¹all porn media has a story, even if people like to joke that its pointless, but that’s a bigger topic for a very different conversation