SE is either blissfully ignorant or they just don't know about it. This stuff does not happen in Japan and i think they don't really care what happens in the west. Yoshi P didnt know that RMT was an actual thing until 2019 or so when he has seen an actual in game shout advertising it lol.
Imagine a new player wanting to get invested in this game and the first thing they get is a 18+ NSFW ad to the face xD
Most players just get the hell out of there instantly. This is one of the reasons why not many new players, that actually want to play the game, join the game.
I have a few friends that even quit because of the new stigma this gamd has nowadays. They find it very disgusting knowing that they actually just play a NSFW game in the end.