I'm gonna assume you're genuinely frustrated and engaging in good faith.

You're right, it wouldn't really be good for all white people to die, unless you're some kind of Malthusian. Oppressor status is not inherent to a lack of melanin, it's just emergent from the history we've built for ourselves. I get it. But that's not what the comments you've linked are really saying. There's some subtext that you're missing - mainly that calling for a genocide against white people doesn't really come with any actual intent behind it due to the obvious absurdity of it.

When some chud calls for the genocide of Jews, of trans people, of BIPOC, that's scary because it's happened before, it's happening right now, and it could sure as hell get to be as bad as it has been in the past if we don't get our shit in order fast. Calling for genocide against a marginalized group while in a position of power relative to the genocide apparatus is terrifying and reprehensible.

However, calling for genocide against the operators of the genocide machine comes with a certain absurdity that we all know is impossible to follow through with. It comes from a recognition that that's simply not how that works. The statement "white genocide" is inextricably facetious.

Given the above, the reason we're all bristling at you is because we (in my mind, rightly) believe that if you're not seeing the facetious nature of calls to white genocide, the only option is that you don't fundamentally understand the relationship between whiteness and genocide.