Look at the rate at which munitions are expended on the frontlines in Ukraine, for example. Those kinds of amounts need the transportation network to be working in good order. Bring down a single major logistics hub, and bad things happen.
I'm not talking about production here, but delivery. For that you need roads and railroads, bridges etc to function. How many of those are susceptible to digital takedowns?
Although factories are also an interesting case if they are not airgapped.