But to WHOM has he proven himself capable? As stated, his field commander may feel that he is qualified, but a full review by the rear brass may find that the field commander was in error, and that the man does not yet deserve a permanent promotion. Authority is delegated to lower ranks, but not all types of authority.
Let’s look at it this way: Let’s say the board of directors of your company fires all of the upper management. They ask you, a lower-level manager, to fill in as CEO until further notice. But you’re only an acting CEO, so you aren’t going to get the same salary, stock options, and other benefits of a real CEO. But you still have to take on the full workload and responsibility of a CEO.
Are you going to be happy with that arrangement? Probably not. Let’s not forget that the military is a job, and things like rank determine your current pay grade and your retirement benefits, among other things. If it was known that lieutenants were forced to work as company commanders as a matter of course, many many officers would become unhappy very quickly, and see less incentive to stay in the service.