You're losing sight of the fact Cadets doesn't primarily exist to put people in the P Res... If people switch over, it's because they wanted to join the type of unit available in the local area and they had their parents permission. Don't break a functional youth organization because the reserves can't fix themselves.
How many people is an infantry reserve unit losing because someone wants to sail small boats or fly a glider? There are more types of cadets than just army cadets... Also, each army cadet corps is affiliated with a local reserve unit, so cadets get exposure to what the unit does. People sticking in cadets likely aren't interested in the local unit if they are staying in an unpaid youth organization over the reserves.
I'm guessing you weren't a cadet, and haven't spoken to many former cadets. Many of us do go on to join the CAF, even if not in the "element" that we were cadets. Cadets doesn't exist to fix the reserves, and encouraging recruitment is way down on the priority list for the organization.
One cadet with para wings in the real world speaking positively about their experience in the cadet programme is worth 100x more than another disgruntled former P Res Pte who joined at 16 to become a ninja sniper, found out their vision category didn't qualify for the trade they wanted. then booted out of their P Res unit because the non-combat arms jobs were already full.
Cadets are the wrong tool to use to generate 16 year old recruits, who can't partake in the adult things being done around them... Make the reserves feel more useful and welcoming to 16 year old kids, and they will likely pick it over a military adjacent youth organization.