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

[Kolsykol]

We see Venat, not Hydaelyn, sunder the world. When? Where? How?

I am pretty sure she was already Hydaelyn at that point.
In SHB when we see the records where they talk about creating Hydaelyn and Venat becoming her heart she mentions that she'll be able to take the form she wants.
So she was already Hydaelyn she was just using the form of Venat the same way that she manifests as Venat when we see her at the end of SHB and the start of EW.

Emet said in SHB that Hydaelyn and Zodiark had been fighting for a long time before the sundering happened, so the way I interpreted it at least is that Hydaelyn viewed the sundering as a sort of desperate measure because the Ancients wouldn't stop turning to Zodiark.
In the big cutscene in EW she should already have fought Zodiark before to a stalemate.
The way I interpreted it at least is that the sundering was essentially an act of desperation to end the circle and because the Ancients kept sacrificing themselves and relying on Zodiark and she couldn't deal with Zodiark without desperate measures.
Otherwise I dunno why Emet would've emphasized that they '' fought and fought and fought etc ''.

Hydaelyn may have had the power to sunder the world as a means to deal with Zodiark temporarily/ imprison him but not kill him.
But it doesn't seem like she had the power to subdue him without such desperate means.
And she had the Ancients just constantly empowering him back again it was a futile effort and fight the sundering from her pov seem'd rather necessary.
I mean either that or start slaughtering her own people I guess?