C.E. Evans wrote:
I actually think the best fit is just that Starfleet personnel can change jobs over the course of their career.
Sure, but those jobs don't correlate much to who is eligible for command, just like the divisions don't.
The only thing is that starship captains tend to be from the command division (unless it's temporary). They don't have to have originated there, but that's where they wind up when starship command is their ultimate job calling.