Book of Erotic Fantasy, Sisters of Rapture, The book of Passion, 5e Guide to Sex, the Lover's handbook, Rolling for Seduction, Erotic Arcana etc. There are a bunch of OGL sex books. There’s also Lamentations of the Flame Princess and the incredibly gory art therein, and tons of other examples. How much of any of those things have ever come to rest above the heads of WotC and official D&D? This is a solution not only looking for a problem but ignoring the actual solution that was already there in order to scream “I am the only solution!”
Well ... the last time D&D was this popular, there was the Satanic Panic (which was both a product of the morality of the time, but also the more adult nature of the product in the late 70s).
And TSR instituted its own internal code to clean things up, and began the process of sanitizing the game.
The reason that most of these things didn't land on D&D's head is because it's been more niche. If you're in the hobby, you know about it. But it's only been in the last, what, six years or so that we've seen explosive growth. And a movie. And TV shows on the horizon.
Kind of a difference.