Schools encourage perfectionism, not excellence. They encourage people to avoid mistakes, not to be creative.
John goes on to argue that schools reward us for our worst performances instead of for our best. Thought-provoking and worth reading if you can act on it. In any case, something we need to think about.
As an aside, one of the great triumphs of modern education is how it has set itself above criticism by making its practicioners far too busy to have any time to think about what they are doing.
The unexamined school is not worth building.