How is this allowed?

[Merrigan]

The difference is that this is not a classroom. Its SE's Job to make this game safe for an 12+ y/o if they lable it as a 12+ game. At least to the extent that you dont see ERP Club Ad's in the Major Ingame Cities containing inappropriate language or/and links to websites/dc-server with inappropriate content for an 12y/o.
Im not a parent myself and will probably never be but if I were I would at least expect SE to work on making the game 12+ conform including community created content.

There's not that much difference, because both examples are based on the same observation: the regulatory authority (teacher / SE here) can't control everything. The parent is needed at all times, because they are the first to be able to decide what is good for their child, and the first to be aware of the impact that an external stimulus has on their offspring.

In the more specific case of MMORPGs in general, your post misses one point: you can't, and never will be able to, completely control this type of drift. You can regulate them, however. Here, for example, you could be tougher on ads in chat, but accept ads in PF (as long as they're honest, which I think is essential if a kid isn't going to ‘accidentally’ fall into a club that's too evocative).

But the all-control you seem to advocate is not achievable. And I've already mentioned another concern in a similar post: outright bans can have disastrous consequences. In this case, banning this type of advertising won't make ERP users disappear. It will just lead to a more discreet practice, and a displacement of the problem (towards, perhaps, even less controlled platforms such as discord). And then we'll be facing a real problem, much bigger in any case than a discreet ‘18+ club’.

Visibility also allows a degree of control, and that's something we shouldn't forget.

Finally, I'd like to reinforce the message of a previous post: MMORPGs claim to be accessible to 12+ children. They never are. If it's not sexual content, it'll be the presence of adults using inappropriate language (insults) that poses a problem; the intrusion of an increasingly manipulative economic system, with the introduction of systems such as payment via livebox on certain games, which is nothing more than an invitation to consume for young teenagers who don't yet fully understand the value of money. And apart from that, the story is often inappropriate. I've seen a number of posts focusing on the presence of sex trafficking in MSQ, and once again I'm surprised by the ultra-focus on sex, which seems to crystallise all the debates on the accessibility of content to children. But what about the mention of suicide during Endwalker? The mention of the end of the world? These are much tougher subjects than the famous big bad sex.