i really echo the part about genocide as an ideal form; something platonic.
when you note something is genocide, people (understandably) default to the holocaust. it is arguably its purest, most ideal form (not as in ideal/pure=best, but as in ideal=essential, most correctly recognized). this is partly because of the trauma of civilization it has done to all of the west. we saw the endgame of racial purity, and (to most people), we were horrified. it's a shock that we can't really move past.
edit like ok i realize after writing this post that i haven't talked about the plight of the jews and the other groups killed in this post; the germans did not suffer like they did. we did not suffer like they did. they have a trauma much more pronounced than us. but we still have collective trauma in our nationbuilding following the reveal of the camps' nature. it's why we call us japanese internment camps "unfortunate" more often than not, instead of, like, an actual terrifying practice. trauma is something one naturally avoids dealing with to save oneself the stress.
the problem then comes when other degrees of genocide happens, people immediately jump to "but you can't compare this to the holocaust!". a big reason the holocaust was such a trauma was that up to that point, the world was arranged around male, european, white supremacy; antisemitism was not unpopular among the allied countries. nationbuilding up & through the 19th century was all about some form of national purity. then we were faced with what that actually meant when taken to its consequences. people intuitively get that when you fight over blood and nation, you are removing groups for the sake of your own, because of your own's intrinsic better-ness. it also means that today, because of civic identity, one gets incredibly defensive when problems with racial purity are pointed out, because people naturally don't want to be associated with the holocaust.
but the case is, rather, that genocide is not one thing, and there are degrees of horror in what it is, from less to more (don't get me wrong, it's always bad; but, to put it in layman's terms, and sorry for that, some genocide is worse than other forms; it's all something that shouldn't be done in the absolute, but it's not all the holocaust). people miss the point that transgressions can be less gruesome than the holocaust, and therefore they can't mediate their response of denial to less than that.
so we get into situations where the actual arguments provided, willing are not, are "well it's not the holocaust, so i'm not evil, and it should be fine", instead of reflecting over the fact that the holocaust is the worst thing ever to happen, without reflecting that that's why the response is as it is, without understanding that you can be doing something wrong even if you're not using gas chambers for it.
i mean, it's hard to phrase. people feel how the holocaust is connected to ideas of national purity, but at the same time, they're not really aware of it. people feel disgusted not just because of the horrors of it, but because at some level, they feel the association with their own nationbuilding, even if this was an extreme form of the darkest parts of that.