It might not be SE's task to nanny this big and mature community, but it's in their biggest interest to make a difference between something subtle and something explicit. We might find references and analogies about sex and other delicate subjects, but they're not explicit and rubbed on your face with images. We have underage people playing FF14 and while SE can't control what those people browse they can keep them from doing more "graphic" acts in the game (SE seems to not give a damn about what ppl already do, but it might be one of the cases of "I don't tell if you don't, so enjoy"). One thing is you mention sex around an underage (it happens), another is your selling /showing it to them. I think SE save themselves from much more trouble by "censoring" and have all those freedom thirsty mature people crying about in the forums than keep it in game.