I agree, almost none of the games I see target kids even if their 'kid friendly' though I personally love the horror here. There is no shame in making low budget slasher films, and should be no shame in low budget spooky video games. There's a certain charm to them that's just entirely absent now. There are of course a ton of actually good or unique horror games too. as far as the visual novel thing, that's probably me your talking about lol.
the promotion thing is a shame really. If itch just followed the same path as other self publishing websites, or sites designed for creators then they could just have an nfsw 18+ part of the forum for adult games to be freely advertised and discussed. I feel perhaps some of the reason that there is almost no reviews, or discussions on less popular games is because it's not actively encouraged.