Ktisis Hyperboreia question [Spoilers]

[CKNovel]

If Elidibus could just open a portal back in time why didn't ascians and crew do that first even if they didn't remember what caused it in the first place? They could constantly keep going back looking for ways to prevent the final days or at the very least assaasinate venet before the sundering. They obviously knew it was her doing

He couldn't, only the modified crystal tower can and he lacked both aether and administrator rights of the CT.
It take a massive amount of aether to transport someone in the past, Alexander would have absorbed the surrounding aether and made the earth around him unexploitable, impossible to live on. If my memories don't fail me.
Elidibus "only" transported the WoL's consciouness.

That said, I really think SQEX initially wanted the WoL to remember the past as Azem but they probably thought it was weird to implement.
Yet it's the thing that would've made the most sense without time travel and memoryWipe McGuffin and keeping the possibility to explore Elpis.
I would have prefered this scenario, remembering as "Azem" and for convenience, the WoL just remembers in their own body.

An altered timeline would be interesting in its own way, but it is inarguably not the story the writer wanted to tell here, or they would have made it happen that way.

And my two personal cents are that utterly rewriting the timeline at this late stage would be poor storytelling. It would be dropping every single plot thread that has built up, without resolution, and re-learning an entirely new world. As a story, it would be unsatisfying, and from a practical gameplay standard I don't even know how much of the world as we know it could exist any more.

Spoilers about DQ XI:

DQ XI just does that.

And it feels incredibly weird to go back in time and solve everything before the crisis.
The most awkward part was how Hendrick character development was simply wiped.