So was the adventure in "Chrono Trigger," but see the fallout from that in "Radical Dreamers" and "Chrono Cross."
I mean, the numerous deaths and terrible fates that befell Yeul and motivated Caius to blow up time itself is actually pretty similar. Not to mention Serah's own slicing of her lifespan. With every correction they made to save the future from ruin, they either shaved off the life of a Yeul and Serah herself, or hardened the resolve of Caius to work harder at blowing up the timeline. So in terms of consequences for everything they did, yeah they definitely went there.
The catastrophic world ending event at what was originally going to be 400 AF in Academia is exactly that. Because Hope got the idea of utilizing an artificially created Fal'cie capable of managing and manipulating time thanks to Serah and Noel being able to do it and fixing the future. That and the whole Augusta Tower quest was them trying to not make things worst and fix the unintended consequence of their travels.
And then of course there's the hilarity and shit with Atlas.
That's kind of the point being made, though. They couldn't know what the precise results would be other than erased events, people, etc.
You're right they couldn't, but at the same time they knew what would happen if they did nothing. Cocoon crashes into Pulse. Humanity ends, and Caius gets to spend eternity with Yeul in a world without time. I mean, there weren't a lot of other options here. Caius was intent on either killing Etro, or killing off humanity to bust open Etro's Gate and end humanity and existence that way. He was a man on a mission with absolutely all the time in the world on his hands.
Obviously the narrative didn't have any interest in exploring these ramifications in any deeper sense, so we're presumably meant to take it as unquestionably the right decision every time they set out to resolve a paradox -- but that makes the narrative decision to show that there are deeper considerations afoot all the more odd since they then still go unconsidered.
Well again, that's what I meant when I referred to Alyssa and the arc with Academia in 400 AF, Augusta Tower, etc. You see those questions being asked and examined, which is why those areas are sorta the most difficult and understandably opaque areas of the story.
Ironically, the non-linear, open exploratory style of XIII-2 which players wanted after XIII, sorta ended up harming the game's execution of it's story because events that would have
benefited being told linearly, were instead depicted non-linearly for players who just sorta did their own thing and went with their gut. So you have certain events that were key to the story being told completely out of order and just landing flat or being forgotten about because the proper sequence of events weren't followed. I think that's what happened to a lot of players who didn't quite get some of the points of the plot. Because I had a friend who played it with me and they went totally out of order and did Augusta Tower
backwards, and it made absolutely zero sense. Then they didn't meet Snow until much later, and had no idea why Serah was concerned or thinking of Snow and worrying about him in a place that he wasn't even shown to be in because they only visited the era Snow wasn't shown to live in.
