Isn't this the truth?
However, the record does not actually support that underlying idea, at least not in a clear-cut way. Of course we can all think of cases where people are in positions in which they clearly do not have the intellectual capacity to understand what the task involves, much less do it effectively. The other side of the story, however, is that of cases where people who were clearly intelligent, well-educated, and intellectually acute have nonetheless made a total hash of things.
Military history, in particular, is full of spectacular disasters where someone subsequently looking at events often concludes that the generals in charge must have been seriously slow on the uptake. (One classic case was that of the man responsible for the disastrous French defeat at the Battle of Sedan, Marshal Bazaine, who was defended by his lawyer at a subsequent court martial with the classic line “Gentlemen, my client is not a traitor. He is merely an imbecile.”)