Though Endwalker's plot differs, I thought the principle was similar to The Dark Forest Theory.

In a nutshell, this theory was first introduced in the science fiction novel The Dark Forest. It posits that the reason humanity has not made contact with any other civilizations in the cosmos is because:
  • All life desires to stay alive.
  • There is no way to know if other lifeforms can or will destroy you if given a chance.
  • Lacking assurances, the safest option for any species is to annihilate other life forms before they have a chance to do the same.

In Endwalker, other civilizations aren't necessarily attacking everyone else, outside of the Omicrons, but in the end they all came to the same conclusion: there is only death. There is only despair and unfulfillment.

These emotions are what Meteion discovers during her travels through the expanse. It's a sobering and terrifying thought. I've posted this elsewhere, but despite its uplifting moments and themes of staying the course, I found Endwalker to be profoundly sad. The universe they find themselves in is a graveyard. And this breaks Hermes' heart. And thus, the Final Days are brought into being.

I don't know if the writer of Endwalker was familiar with the Dark Forest or not, but some of the parallels are striking. And as an aside, this could potentially open up some great stories for the game in the future.