Let's play a game: Save the Ancients!

[LilimoLimomo]

And then from there we start delving into the idea that if it hadn't been Hermes, some form of calamity would have come along and obliterated them at some time another because of the nature of their powers and the flaws of their society. But then that ignores two things: that the Ancients lacked any real capacity for growth or perspective, which flies against near enough every interaction we've had with them bar Athena, and that mortals themselves are not inherently at risk of the exact same possibility.

I agree that modern day folks could still potentially destroy their societies and/or the world, but the risk is significantly lesser. When most members of your society are born with the capability to single-handedly end the world, all it takes is a single person's poor judgment or dissatisfaction to trigger a world-ending catastrophe.

Meanwhile, there's a whole lengthy scene in Stormblood showing that it takes an army of mages and more to do something as simple as break through a big metal door. It takes modern day folks orders of magnitude more effort, time, and organization to generate the kind of threats that the Ancients could with a snap of their fingers. And that's important, because the need for lengthy timelines and supply chains and communication all create additional points of failure for such threats, making it easier to detect them, react to them, and dismantle them. To achieve the same destructive means that Ancients could simply wish into existence requires the consolidation of a great deal of power now, and since very few have access to that amount of power, that reduces the number of potential sources of destruction.

So in summary, there are vastly fewer who have the potential to destroy the world, and it takes them a lot more time and effort to do it which makes it easier to intervene and prevent or prepare for such plans. Compared to the world being endable if any single person has a sufficiently bad day, the world is much safer now.