What does this accomplish? I genuinely don't understand why this fallacy is so common, even trying to come at it from a psychology perspective.

Something being shocking is not the same as something being unforeseeable. Being shocked by shocking behavior doesn't make you some kind of idiot. Acting as if having emotions about immoral behavior is beneath you is self-aggrandizing.

I'm sorry for my tone, but I'm sick of this genre of internet comment in particular.