What's the point with that quite lackluster story in Endwalker?

[Absimiliard]

And regressed them back to a state of sub-human intelligence and capability (talking post-Sundering here, not a swipe at mortals, lol), leaving them to rebuild mankind and civilisation all over again while instilling herself as their guiding figure, and all of the hardship and suffering that entails. All of which is what I'm referring to when I say a direct conflation of IRL events with what happens in game is a bit of a false equivalency to make - and it's not to her benefit.

I can see where you're coming from given some people feel some kind of way about some rather nasty historical events, but I don't think most people using the term in relation to this are trying to make any kind of comparison to prior atrocities. I believe they are using it only with the textbook definition in mind, nothing more. Doesn't mean people won't make the connection on their own after reading the word, but you get what I'm saying. Regardless, I still don't find the term appropriate based on its definition.

Genocide I can understand, but I'm not certain if omnicide would necessarily fall under the same umbrella. As it stands, the term has not been applied to any event in real life. Nor could it be, because it would mean we were all dead. It has, however, been used in fiction on a number of occasions.

As an aside, have you played NieR Re[in]carnation by chance? If not, it might be worth taking a peek at the lore they hid away over there as part of the crossover event. It ties in nicely with what you said about the state of mortals immediately post-sundering, though I suspect you already have given how you described what they were reduced to.