It was often said that the golden age of man coincided with the Eldars height but I think by that point the Eldar had become insular, isolationist, and insatiably kinky(fuck murdering Slannesh into existence) while humanity was an active leader in galactic affairs with the old human federation being you know at the height of its power.
And while I'm not saying chaos is at all good the gods themselves forget that they have positive domains and things. Khorne is honorable and also very straightforward. Tzeentch is straight fucking insane but he is the god of progress, and Nurgle is the god of life and stability (though he often takes it to cancer and endurance rather than healing) and actually genuinely love a lot of his followers
Just as the chaos gods affect the universe so too does the universe affect them and if it wasn't for Slannesh kicking them awake they wouldn't be making this crazy negative feedback loop of endless war
The argument one could make about the Emporer being a god of order is that in many mythologies Chaos specifically births Order or some form of stability like gods of concrete concepts like earth or sky
That is a bit of a chaos-positive way of putting it. In the end Chaos is the manifestation of the old Aristotelian notion that evil is extremes, that it is too much of a good thing. So sure if you moderate Khorne you get martial honor, but that is not Khorne anymore it is some other saner war god. The actual Chaos Gods only use their so called good parts as a gateway drug for the gullible and the desperate. They do not have good parts only parts that are not immediately obvious as evil.