Like are we talking about people who believe that all the world’s issues are caused by meddling and scheming of the genetically inferior and rule of the world is the birthright of some genetically pure ubermenschs

Strictly speaking, they believed that grouping of people by race makes sense in respect to their personality, and thus some common racial interests, and then that thus races compete fight each other, and then that thus they should make their own race "win". Genetic "purity" was in their opinion needed to preserve "their" personality traits, or something like that.

That's still bullshit, but with my description I hope you can see that it's more similar to class theory in Marxism than Marxists would like to admit.

That’s not happening here, but I’ve seen so much of it that it shades how I interact with online discourse.

Well, for me any kind of contempt for the weak (in any respect - appearances, sicknesses, hard childhood, trauma, unpleasant personality, anything) is reminiscent of people who dismiss anybody with a problem with no objections from their conscience, also thinking that such behavior makes them stronger. And I know that maybe they'll regret that in the old age, and that those they dismiss will later praise the universe that they've been dismissed by such people, but still.

And fighting that contempt for the weak I don't see as potentially harmful, while attacking somebody who's doing it is in my opinion and indicator of being the bigot in question.