It blows my damn mind that there are people here who don't understand this concept.
Considering that almost every other type of content has a category of its own, I want a genuine answer about what type of party the roleplay PFs are "hiding". Is it a recruitment advert? If that's the case, I could be really pedantic and say that recruiting for a static is actually a social feature, since you aren't intending to run content immediately and you're instead trying to organise a group of people to attend events at a specific time. Which, gee, if you phrase it like that... sounds identical to the roleplay PFs, which are people organising parties for people to attend events at a specific time in order to do content. Are we going to tell people recruiting for a static to go use the Fellowship Finder, too? (No, of course these people aren't, because everybody silently acknowledges that while Fellowship Finder is nice in principle, in practise it's a little bit lacking.)
What other kinds of parties could the roleplay advertisements be hiding, if not static recruitment? Can't be FATE parties, they have a category. Can't be Treasure Maps, they have one too. Eureka and Bozka? No, they have their own. Unsynced BLU alliance raids? Oh wait, that just shows up under the Alliance tab so no, can't be that...
I'm not even being sarcastic when I ask the question: what parties are the RP adverts actually hiding, when almost every other type of content in this game has its own tab and every single one of those tabs will show up higher on the "All" PF list than the "Other" tab does.