> First time I've ever heard these two things talked about as a matter of "this versus that" and not "combat and logistics".

Not sure if you’re being sarcastic? Or haven’t read much about the military and are assuming?

Combat vs combat support vs combat service support (logistics) is a very common and very significant distinction to make and usually matters a lot for a great many things.

Has a logistics branch officer ever led a major Army? We had an artillery officer in the UK and even that was a talking point at the time.