All of it is GW, who owns 40k and is just as willing to bend its own lore for money.
Remember how not even the emperor could improve so quickly the space marines? Cawl did it.
How they're losing technology and regressing into barbarism? Cawl invents things.
Guilliman gets put into super power armor fueled by eldar blood magic to keep him alive, and they lock Magnus in an isolated webway like 5 minutes after he shows up.
Why am I even wasting my time doing this? You don't care, you're only a shitposter. Have an eldar.