Flaser might be right on the economy angle, however there is something he forgot.
This wasn't a battle over resources, it was a poltical war. Political wars play to different rules than traditional wars, meaning even a tiny ball of rock floating around on it's own can quickly spawn massive battles quite quickly. Every planet, whether habitable or not, is a target to be taken and held, meaning the ground war is likely a monstrous operation, and where most of the casualties are made. That kind of loss of people harms any economy, including space based ones.
Needless to say, this was a very, very unpleasant war, especially at the end.
