they can't pass some mythical fitness level that has no impact on their operational employment.
Aircrew. Due to the nature of the job, a basic level of fitness may mean the difference between found dead not far from your wreckage because you've jacked it in or being able to E&E and recover out of harms way. I'm not on about Bravo 20 stuff, just a bit of physical robustness.
Groundcrew. Because our Armed Forces are tiny, over stretched etc, anyone could be called upon to carry out other duties away from their own comfort zone. Basic fitness may not only save your own skin but more importantly, someone elses. Do I need to spell it out?
The CoC need to know that the blokes and birds below them are at least at a basic level of fitness to be able to deploy. The new buzz word being 'duty of care'. Old school being able to carry out your job without having a seizure.