MILITARY SERVICE REQUIREMENTS

[beez]

I know nothing about the military. Aren't there non-combat support roles that these people would be completely capable and qualified to perform?

Yes, they are called civilian roles.  

Civilians of all stripes can and do work in military environments, usually as support personnel.

I'm a fat old man.  Bad back, bad knees, can hardly walk some days.  Should I force the NBA to hire me as a star center?

I'm sorry, that's a ridiculous analogy and a conflation of the question  The vast majority of personnel never see a battlefield nor are they in an area of conflict.

The vast majority of people hired by the NBA never toss a basketball.

Is there a point here somewhere?

Let the people physically and mentally capable of doing their job, DO their job.