An all crap horde army or an super elite force both suffer a little - which is likely correct, but hard to balance with any points system due to luck being a factor.
Yeah, my Goblin army is all Discipline 4, while not a crap horde (it's an average horde) it does mean that nearly half the dice you roll will be useless. Having a third, 3, a third 4, and a third 5, would be the same amount of points (all things being equal), but would make much more sense mathematically.
There again, Goblins can only count up to 4, anyway.