I haven't seen WotC putting R or X rated content in the game though. Although, as we've pointed out, they have all sorts of nasty things in the game. Curse of Strahd has genocide, domestic abuse, child abuse, drug abuse, and there's some pretty icky implications with Strahd's attitude towards consent. There's even a holy man who creates what's essentially a child bride in the hopes that Strahd will be happy with her and leave other women alone.
I agree with you that WotC shouldn't put overly graphic material in the game beacuse it doesn't fit the tone of what most of us are looking for in a high fantasy game. Our disagreement is that I don't believe slavery is a rated R or X topic. I don't have a problem with an evil organization, like those dirty Lloth worshipping jerks in the Underdark, being slavers. Not even when it comes to teenagers playing.