If teachers of classical music transmit the past, then perhaps older teachers have more direct connection to traditions further away in time. But the culture of the conservatory has changed: the oldest musicians were highly venerated teachers, now they may not be.
In traditional conservatory culture, teachers died on the job. Now some celebrated schools strongly encourage older artists to retire — or even dismiss them.
The longevity of musicians as teachers was often economic necessity. Concert fees might dwindle. Now the major schools offer retirement plans and health insurance. Many European schools observe mandatory retirement ages, with a few notable workarounds.
Our society places small value on elder wisdom today. We prefer innovation. And maybe learning classical music doesn’t depend on direct transmission of past techniques or artistic thought…
Just as it may not make sense to value someone just because of age, it doesn’t make sense to devalue them either.