The Wasteland is titled "for things that don't fit in anywhere else," which means exactly what it says. Anything within rules can be posted; this includes "shitposting."
But it's not even unnecessary posting? It's posting something that someone found funny and wants to share with the community. Just because you don't think it serves a purpose doesn't mean it doesn't serve one. And the Wasteland is the best place to post something like that.
Maybe rather than a whole new subforum or something there should just be an official shitposting thread. Then people could do all of it in one contained, controlled place.