It's hard to integrate porn into real-time gameplay (you only have so many hands, after all) so the only thing most games go for is turn based RPG or some weird time wasting menuing bullshit. So it's not too important for me.
I don't think you can really say it's not "realistic" for one guy to do the writing and art for a VN considering how may of those there were before the rise of AI. Hell, I've even made a few myself, so I know it isn't some impossible feat.