I think they may be ranking Hitler the artist or Hitler the leader surely. It can't possibly be the more simple explanation of the internet being full of trolls who think anonymous graffiti is funny.
Why is it only on HN that this sort of contortion happens?
Though yes it's the internet, so it's probably mostly people doing it for the funny.
Conflating Elo ranking with goodness is shockingly dimwitted - I'd think it much below Hacker News commentators, but apparently that's not the case. Of course Hitler would have a high Elo ranking; he's objectively one of the most powerful and influential humans of all time.