It does does it? Although I personally would say that the gun should be MORE accurate to help offset the human warfighter conditions cited, this begs the question: what assault rifle combination is LESS accurate than an AK?
I've owned FAL's that were less accurate than most of my AK's, although on average an FAL is probably slightly more accurate. In my experience, a typical FAL is about a 2-3 MOA rifle while a typical AK is about a 3-4 MOA rifle. Your average rack grade Garand isn't going to shoot much better than that.
It's also really not practical to expect much better accuracy than that on a large scale, since most military ammo isn't match ammo and never will be.
What makes more sense is to make the weapon itself easier to shoot accurately under bad conditions. Good ergonomics, adjustable stocks and optics are all things which will have much more impact than making the rifle itself slightly more accurate since we're talking a difference of maybe 2" at 100 yards. Even AK's are more than accurate enough to make head shots at 200 yards and torso shots out to 400. The main thing handicapping them isn't inherently bad accuracy, but inherently bad sights and bad ergonomics.