The fixposting thing is funny because it lampoons part of the vtuber scene. Like how chuubas will pretend to be pure, untouched maidens to appease unicorns or post lewds of themselves for coomers, they also play up how dysfunctional and "broken" they are for saviorfags. "Oh, look how ditzy and hopless and socially inept I am! I live in filth all alone! I'm just a bird with a broken wing, tee-hee! Can YOU can save me, anon?" And just like with the others, they do this because it appeals to a certain type of lonely person.
Important to keep in mind, though, that it is just a joke. Here, at least.