Endwalker's story had me, but lost me. Ethical issues especially (spoilers)

[Ryaz]

Why do people still keep insisting that if you change the past, you erase the future? We know for a fact that this isn't the case. It's not called a split timeline because one is erased, it's called that because they both continue to exist at the same time.

EDIT: So folks know what I'm referring to: https://na.finalfantasyxiv.com/lodes.../sidestory_08/

tl;dr: Eighth Era timeline, the one G'raha allegedly erased, was not erased at all. The timeline split, and now there's two of them. One where the people of the Eighth Era continue to live on, and one their future never came to pass. They exist simultaneously, neither merging nor negating the other's existence. I can not stress this enough. Nobody was erased from existence because G'raha changed the past, and nobody would be erased from existence if we set the people of the Unsundered World upon a different path. Best case scenario, we make like Future Trunks and dip back into our own timeline. Worst case scenario, we're stranded there—in which case things get very bad for the people who were counting on our return.

Well, if the WoL did change the future, wouldn't they return to the new future like G'raha did? Meaning, they wouldn't bring the answers back with them as to the cause of the Final Days (might not return at all actually) and would doom that branched path to annhilation by the Song of Oblivion. So that source and shards would be destroyed while possibly saving Elpis.

I also have to wonder how many people decrying Venat as a monster thought embracing Zenos in his final battle, and not having the agency to walk away (despite him saying he'd accept it if you did) was a good thing.