It feels so real in how disappointing the experience becomes for the straight characters.

This hits the nail on the head. It’s funny because of the point of view of the actual participants.

The funny thing about this thread is that there are so many comments essentially agreeing with the central premise of the sketch, that it’s relatable and disorienting when you stumble onto some kind of established fandom and can’t seem to keep up with why it’s popular or what is or isn’t “part of it.” The popularity is confusing in itself, and the need to dissect the lore (as OP is doing, perhaps even unintentionally following the sketch itself) distracts from the original purpose of going there to be entertained.

In other words, the sketch is funny and relatable exactly for the same reasons why much of the audience doesn’t find it funny and relatable.