It's also a hell of a lot easier to disrupt said monolithic support structure. Army travels on it's belly.
Not sure that that is true anymore. For example, I haven't seen any truly successful disruptions of the US supply chain, even though Al Qaeda is perfectly willing to blow themselves up to take out trucks. Modular and standardized supply chains guarded by well trained troops with highly specific regulations (+ sniper towers) create a pretty damn secure situation.
It'd be more accurate to say that armies today travel on their diesel. Disrupting diesel shipments has happened occasionally, even for political reasons. I can't ever recall hearing of troops going hungry or thirsty.
Did you know the US spends more on its military than every other country in the world combined?
Yeah, just look up how much they spend in Iraq and Afghanistan on A/C alone. That by itself exceeds the GDP of a helluva lot of countries, let alone our entire budget.