Excellent article, George Dillard.
History is full of talented folks who have stayed way passed their time to move on -- Winston Churchill, Queen Elizabeth II, FDR, Rudolf Nureyev, and the list goes on.
The older and longer they are in powerful positions, the more entrenched they become. Younger folk see other lives for themselves -- an example is Jacinda Arden, who resigned as New Zealand PM at age 42.
People need help to pack up and go. They have to be eased out or pushed if that fails. Because, as you write, the stakes are too high should they be allowed to stay and occupy that can be better done.
The current example is Joe Biden. He is about to slip in the announcement that he is running in 2024. He shouldn't because the country can do better with someone younger and more talented.
I invite you to read “Award Joe Biden with Another Term?”
Many thanks. Best.