What lore do you ignore?

[Cleretic]

Venat's whole "I had to sunder the Ancients to make them more capable of wielding dynamis" bit. It just feels so... tacked on.

What about the reasons for the sundering that she actually said, though?

In the game across both Shadowbringers and Endwalker, it's never one of the multiple reasons stated for why she did that, internal or external, and it only comes up in passing in the EE3; it's actually Y'shtola that points it out in-game, Venat just doesn't deny it when asked. I actually read it less as a primary motivator, and more as an important consequence.

I think it comes up among the developers and the EE3 because, from a sequential storytelling point of view (and the in-universe historical view), it's one of the most important effects of the Sundering. While on Venat's side of things, yeah, I think it was lower on the list.