I've been thinking about smallwhitecat's and tether's explanations. And am just pondering.
One of the things about it, though, is the nastiness. Not just mn, but generally, in the culture. Is it on the rise? Probably. If it's on mn, it'll be out there, in RL. It's hard to put my finger on it, so I'm going to use an image. And I apologise in advance, because I've been reading another thread - and there will be no prizes for guessing which one.
There really is something of the pointing of a sharp stick through the bars of a cage to it. So, although resentment may be a part (smallwhitecat's point, I think?, unless I'm misrepresenting you) there is something in the nastiness that makes it clear that the perpetrators are aware of a power imbalance (they are able to poke the stick, at the people in the cage).
Which means that, if it were resentment, it's a weird resentment, because the way it plays out makes clear that there is, actually, not so much to resent, because those who are poked, are caged.
So, it's a pseudo-resentment, masking simple cruelty towards the unfortunate and less powerful.
(And I think that brings us near to tethers' interpretation??? And apologies to you, tethers, if you think you wouldn't like this slightly baroque image-explanation anywhere near you!)
(I do wonder if the above makes any sense at all.)
(But sometimes mn is nice as a place to sort of talk to yourself, in company.
.)