Thomas Shey
Legend
I suspect if we look at the actual examples of this they will be a lot more specific and less general than you're suggesting.
I.e. someone will be moaning about a game having a D&D-like class and level system in one thread, and then suggesting that a game should use an HP system like D&D instead of an more elaborate death-spiral-style damage system in another. I very much doubt anyone is saying "Class and level sux" in one thread and then "Class and level rules" in another unless they are true agent of chaos!
Well, it doesn't help that some people are simultaneously critical of D&D, but really vague about what parts they don't like and whether its a generic dislike or a contextual one. I try mostly not to discuss my general dislike of D&D proper (and to a less degree of its kin) because I'd have to unpack what specifics I dislike and to what degree and that seems excessively negative, but at least if I'm going to diss D&D, I won't do so in the broad and casual way I see some do (I can't say I did this many decades ago when I first decided it wasn't my gig but A) I've come to tolerate some elements more than I did then, and B) I was young and even more cantankerous than I am now).