While I'm not here to dispute how offensive it would be, for point number 2, I would argue that The Backrooms, (on this wiki anyway), don't actually make any sense in the first place, so that would be a moot point. Especially in the negative levels, such as -2, in section 'The Hall of Dull Flames', where the distorted sound of classical piano can be heard and everything is a painful blue. Secondly, while this isn't quite relevant, I wouldn't think every last disappearance would lead people into the Backroom, I'd say only a handful every century at best, but, this is a collaborative wiki so, everything is pretty much up in the air.
Lastly, considering this Wikipedia exists, I'd say the Backrooms are becoming common knowledge. (Also considering its fiction, but, that just ruins the fun of it, doesn't it?) P.S. The phrase 'for all of time' is meaningless in the backrooms, considering Time is irrelevant in the backrooms. People from 1300AD are still alive in it, at least. The backrooms aren't supposed to make sense, so why not just go with it? hell, the whole premise of its entry is to 'noclip out of reality', in its own words.