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

[KizuyaKatogami]

What we don't know is how it affected them. We do know that the Ancients planned on killing people.

Intent matters. Someone who intentionally commits a murder is morally worse than someone who commits a murder unintentionally.

If there is no excessive and unnecessary force, then there is no need to argue about collateral damage. Venat did what she thought she had to do to stop the others from making that final sacrifice.

We can infer based on the shb shorty story that illness was a foreign concept to them, however we know illness exists in the sundered world, along with a lot of the aging down process. So we know illness and the short lifespans can be equated to the sundering which puts a lot of blood on Venat’s hands, more than the sacrifices ever would have caused if we count all the shards.