It's a good question and the answer is hard for folks on the outside and also the inside to understand.
"Universality of service," which includes the ability to be deployed anywhere at any time, is the gold standard. Especially in a small force like Canada's. That said, there are positions which must be filled which could easily be filled by people who don't meet the standards. (And you should note that the medical categories for different trades and classifications do vary. Some need better vision or hearing than others - and so on.)
Yes. There are many institutional positions in headquarters and on bases which could easily accommodate someone who can't serve in the field. Unfortunately that means those who can serve in the field may be stuck there forever rather than be rotated around to gain experience (or maybe just be given a temporary break away from the field)
The problem comes in with drawing the line. Especially when you start dealing with the needs of Human Rights legislation and and individuals' unique case situation. An employer's lowering the bar for some cases to make an exception, may soon become the new standard applied to everyone across the board. The corporate position on where those lines are change from time to time and similarly the way that the standards are applied at the lower levels may very from person to person who is required to apply those standards.
The CAF has a very complex mass of orders, regulations, directions and policies and they can be difficult to interpret at any given time even if well written (and many are not).