But what's the point? Imagine damage ranging from 500-1500. You randomly get 560, 630, 720, while your opponent gets 1350, 1450, 1200. It would be better if everyone had a random range from 800 to 1200, and that would be normal.

Not to mention what an imbalance it would create in single-player.

The 500-1500 range would only affect Necropolis. Other factions rarely accumulate such large stacks or have a smaller damage spread. But for Necropolis, this spread will slow down the accumulation of skeletons, so in the endgame, there will be fewer of them on average. And Shakti will be less effective at the beginning (due to the same loss of troglodytes). As will Conflux, which will be less confident in attacking with air units.

And in single-player, do people even play with HW_rules?