I can sort of understand why tbf. Just playing the devil's advocate here but the issue is that today it's fine and shitposts are shitposts but Poe's law will come into action at some point.
That's not the actual reason. Hexbear was openly advocating for their "army" to brigade other instances once it was federating. It just so happens that the basis of that brigading was going to be political.
Lemmy.world pre-emptivly decided it wasn't worth the hassle of having to deal with that.