[FrankTrollman]

Remember also that a low resource army can be left unrecruited as a big pile of gold and popped up on short notice later on. The oni who cost 25 gold and 1 resource are often a crap deal. But if you get an event that gives you 3000 gold you can burst out quite an army in a surprising place on short notice. That's valuable, and well worth noting that the unit exists even when you don't normally use it.

There's no way to see how much gold an opponent has in a pile, and gold reserves don't cost upkeep. While a hopplite army takes many turns of effort and costs upkeep along the way, a large army of crap is free and invisible until it exists in full.

-Frank