Don't forget Nimitz, Halsey, MacArthur, Eisenhower, de Gaulle, Roosevelt (the General), Bradley, Marshall,........and many others who were all over 50 when they won WWII.
MacArthur never left his couch except to abandon his men to the death march. He was a fraud , and probably the best example of incompetence supporting this article. Despite having advance warning, he let his Philippine command be decimated by the Japs. Most of his soldiers hated him. Now, Patton..his men are still proud to say,” I was in General Patton’s Army.”
The problem is the explosion in the size of the upper ranks of the officer corps, and their attendant staffs. There are now MORE flag rank officers in the military than their were in WW II, when the US had some 13 MILLION people in uniform.