As a career manager in the Canadian Armed Forces, I found universality of service was always a concern. It all depends on the numbers of people you have and your ceiling and manning levels within the military. In the old days, we retained all sorts of people who were in the medical category and did very useful jobs in garrison for us as a regiment.
There was always a place for them to be employed. But as the military reduced, those opportunities became less and less. If you want to take operational individuals and you want to move them out of the operational theatre so they get a break from operations, and they need a break from operations, what shore billet do you have to put them into if you don't have the spaces for it? It becomes a push-me, pull-me situation.
I fully agree that accommodations can and should be made with universality of service.