There is an onslaught of femshep/Liara fanfic in the ME community, and it's based on the actual romance line you can follow in the game. (...) But you're honing in on a mildly tongue in cheek remark to ignore the point that claiming sex scenes don't belong in Forgotten Realms because of the IP's history entirely ignores all the lore of Forgotten Realms and the history of D&D,
Sure and fanfic is not the same as game content. It is irrelevant for me what fanfic players will draw and wrote for BG3.
I also can't speak for D&D as a whole, as my contact with it are just cRPG adaptations, like Baldur's Gate, and what appears in another d&D property doesn't automatically make it a good for for another.