That is pretty much exactly my point

So if we look at what the darkness is, darwinism (hence forth known as Tolands law), how does that relate to its counterpoint, ie the traveler? Well what does the traveler do? When it finds a particular race it deems worthy it accelerates their evolution sending them into a golden age trying to break that cycle of evolutionary extinction. In its attempt to beat the darkness it may have inadvertently created humanities replacement. The Vex (I believe the Traveler created them to transform planets for chosen races) upon becoming sentient realized the truth of Tolands law and built the Vault of Glass. It makes perfect sense that the Vex would become obsessed with writing themselves into the fabric of time. By doing so they would ensure the survival of their species. Which would make them a species that is could replace us, therefore they are evolution and that makes them inevitably a part of the darkness. Now the question is what about the Hive? Aren't they infused with the darkness as well? Simple answer yes! When dinosaurs were wiped from our planet homo sapien wasn't the only one to step forth as a contender for dominance. So the darkness is a bit existential and corporeal at the same time. Let's not even get into the other law of the universe, Entropy.

Exactly, the traveller uses over races to try and beat it, the vex weave themselves into the very fabric of time to beat it, the cabal are trying to use brute force to crush everything to beat it, the hive I beleive tryed changing themselves or another species to effectively become the pinacle of evolution but instead they inadvertently created the first hive which devoured the rest of their race, the fallen are just stuck in the middle of everything and we are just another one of the travellers puppets but as Toland suggests at the end of the grimoire card the only real way to beat it would be to unite all races under one banner.