Most modern countries contemplate the notion that at some point in your life you are deemed unfit of occupying an active position, regardless whatever experience an individual may have in whatever field.
What that does not imply is the individual being rendered useless. Highly experienced individuals can act as teachers, mentors and advisers, sharing experience but with no weight for actual decision making or action taking.
I myself don’t intend to reach retirement age and turn off all switches and just stay home and vegetate; I think I can make myself useful up until my body becomes too frail and my mind breaks. But there is a point where I don’t want to have any responsabilities towards an institution.