Too many folk continue to drive when they should not be. We need mandatory retesting for everyone.
The first statement is no doubt true, but does not support the second statement, a silly knee jerk reaction.
What we need is a system where when people are diagnosed or suspected of dementia there is mandatory reporting to DVLC and those people, the higher risk ones, are subject to more rigorous requirements for testing or doctors approval.
The solution should be focused on the problem, not a random idea plucked out of thin air, otherwise we end up with ideas like “Cyclists kill too many pedestrians. We need mandatory registration and insurance for bikes”