The Reasoning behind The Sundering? (*6.0 Endwalker Spoilers*)

[Cleretic]

Confirmed what? All he said was Venat believed the ancients would probably be heading for the outcome of the other civilizations. That’s without her even intervening though. Had she let the truth out perhaps they would have flourished. Instead she allows the calamities to take place and for millions to die.

He confirmed a lot, actually, the answer to that question was LOOOOOOOONG. And part of it was, indeed, 'this was the only plan that would have worked for the end she was going for'. Venat's plan was the only way to stop Meteion.

However, then you come to the question of 'was stopping Meteion necessary', since Zodiark was essentially indefinite protection; she was a non-factor until Amon made her one. There is no one answer to this question, because both Venat and Emet-Selch were flawed and imperfect people with flawed and imperfect outlooks. Neither of them were 'right', morally speaking.

But Venat's plan was the only one that would have worked to stop Meteion. You can't just declare there to be a magic better option, going against the writer, director, and all voices in the narrative itself if you're intending to have a constructive conversation about things; Yoshi-P, with extensive information from Ishikawa, declared that to be the only plan that would've worked, and the entire story says exactly this as well. Declaring all of those sources to be wrong basically just leaves you writing fanfiction.

And that's without going into specifically how you've decided things would've turned out to be better, because 'telling everyone' is pretty much the very first thing Venat shoots down after Ktisis, for the very good reason of 'this would make people freak the hell out and not do anything productive'. The Ancients are not as a whole rational actors, or if we're honest really all that smart. They do not handle extremely bad news especially well, as we see directly in the post-Elpis cutscene.

It is not useful, productive, or even true to declare there to be a secret, better third option.