You know, at first was going to say I disagree, but then I realized that you might
In my experience most otome games used to be
cutesy stuff on par with shojo manga (at most, dramatic, but not dark: https://vndb.org/g542?m=0&f=N18gwcomplete-&s=320
In the last decade, "batshit insane" stuff (but not on the level of gore and degenerate sex acts so nothing grotesque) has become more common; I think it's a way to put "riskier" and therefore more interesting "adult" content in all-ages games.
Since otome games are a much smaller niche than galge*, it's easier to find the darker stuff, whereas if you look at galge, which has much more variety, unless you're specifically looking for the fucked up and obscure shit you'll rarely come across it; cutesy but sexually suggestive content is more mainstream when it comes to galge or harem anime. There are often darker story elements in all-ages otomege, but in a romanticized or melodramatic way and not intentionally edgy and disturbing, so in that sense I definitely agree, because when you analyze those elements more critically you realize how insane they actually are even though they're not presented as anything special. But Diabolik Lovers, which is relatively super-popular, is an exception, perhaps due to its production value, "stylish" edginess, being an Otomate/Rejet game, its merchandise and marketing (paradoxically, its dumb protagonist is universally hated for being a total doormat).
However, "batshit insane" elements can also be found in many of the most popular galge (https://vndb.org/v?q=&ch=&f=020781Ol81Qr81Xkx81Xn081Xn_81XB881XBrN19a0i&s=33w
Speaking of which, I've recently read a yandere TL manga (teen's love, a genre for adult women). I usually avoid yandere because I think it's boring and cliche, but this one initially caught my attention, because it was silly, cute and hot. Then, after I got attached to the characters and fully invested in the story, it got to the really fucked up part, anPost too long. Click here to view the full text.