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

[Cilia]

The point on perfection wasn't that people should strive for it, but that they shouldn't, because it's an impossible concept. Strive to make the best of what you have, to be better than anything that came before you, but not perfect. Never perfect.

[The Ancients] learned all there is to learn about the nature of sentient life and the fates of the stars themselves.
Once a civilization has fulfilled the basic requirements for survival, it will inevitably seek to eliminate all forms of negativity and achieve perfection.
And therein lies its folly...and its downfall.
For perfection is an unattainable ideal. 'Tis the paradox of the immaculate carrot.
Yet civilizations since time immemorial have deemed the pursuit of perfection as “progress.” They pay no heed to the costs incurred in their futile quest, and all too often become the architects of their own demise, their dreams forever unfulfilled.
What, then, is the alternative? The answer lies in knowing that our existence can never be perfect. To be content with what we have and make the most of it.

Whether you agree with it or not, that's the stance the story takes on civilizations and perfection.

[Lersayil]

The point on perfection wasn't that people should strive for it, but that they shouldn't, because it's an impossible concept. Strive to make the best of what you have, to be better than anything that came before you, but not perfect. Never perfect.



Whether you agree with it or not, that's the stance the story takes on civilizations and perfection.

While I don't disagree that that is a message the story implies, I would like to point out that you quoted a very biased source, being a creation of Venat itself.