(MAJOR SPOILERS) Just beat Endwalker MSQ...

[Jeeqbit]

It's not even genocide, is it? Because she doesn't kill them, she just sunders them. Many of them are about to sacrifice themselves anyway.

Eventually the sundered souls die of age, but so too do the Ascians return to the aetherial sea when they feel their duty is done.

[Gemina]

It's not even genocide, is it? Because she doesn't kill them, she just sunders them. Many of them are about to sacrifice themselves anyway.

You can try to use yourself to answer this question: If through some kind of magic your soul or essence is split, and your conscience (thoughts, memories, etc.) along with your corporeal form cease to be, would you consider that a death?

To say the sundering is not genocide is to say that the sundering is non-consequential. Perhaps in terms of the flora and fauna; beings that simply exist, and are purely instinctual, but the sundering carried dire consequences. The WoL is now eight times rejoined with their original aether, and still has no recollection of their life as pre-sundered Azem. We do seem to retain behavioral traits of the previous Azem, which suggests there might be signature values to a soul, but it could also be pure coincidence considering these 'signature traits' of Azem can pretty much be applied to anyone with an adventurous and selflessly good heart in the same manner it applies to every gamer playing FFXIV.

It's just been confirmed for us our soul used to belong to the previous Azem. Convenient to say the least, but it now belongs to us, the WoL. This can be twisted and turned all kinds of ways, but will always end at 'you are you'.