>>718251170
It was microhell when both armies were of comparable strengths, but glaringly so when your strength was just zerging.
That being said, if your armies could largely do battle on their own and clear zerg rushes with relative ease, then you could do some light micro and force the enemy to micro many different battles all at once and exhaust themselves into making very dumb mistakes and lose focus on the whole picture and instead focus on however many little ones there were going on in the map.
Doing heavy micro is an advantage, but a shrewd tactician can force their enemy to be overwhelmed by that advantage to be blind to an incredibly simple strategy.