I, for one, welcome our new insect overlords.
From what I can tell, jokes are not tolerated here because they lower the signal-to-noise ratio. It's not that HN voters are humorless, it's just that they don't want HN to be a place people come for humor, because there's plenty of other spaces on the web for that. I'm starting to think of it as a college discussion group - you go to learn, not to hear Simpsons jokes.
Also the "overlords" joke has a long and tired memetic history in the hackersphere, which would explain the quantity of downvotes.
also, jokes are ranked differently. if you make a non-joke comment that is polite but not very interesting, its score will probably stay at 1. if you make a polite joke that isn't funny, it's probably going to get downmodded.
that might seem cruel, but i'd say it's necessary. a joke that falls flat tends to drag down the level of commentary.
Snarky, overplayed comments are never well received here.
Even less well received are complaints about being downmodded.