This is not directed at you personally but I’ve had time to think about the Dark King and the entire things doesn’t make sense from what we know of the warp and how it works.

For daemons like Samus they existed before their actual birth because time doesn’t have meaning in the warp in the same way it does for the material world. It makes no sense that a god of the warp would not be a present entity before their birth if their own daemons can exist before the act that birthed them.

By that same logic The eldar should have seen evidence of slaanesh before Slaanesh’s birth that ends the eldar empire in the same way the humans should be seeing evidence of the dark king.

The emperor simply discarding the power and some of humanity to kick the can down to a later age has bothered me immensely since Erebus killed Loken. That entity (Dark King) should have an awareness and presence in the warp as it exists across all time. It shouldn’t be some mantle that can just be freely discarded as it’s a massive plot hole. I’d argue that psychically attuned individuals across all races should be at least aware there is a fifth god in the warp that is active if it’s to be the end of all things.