Many people like to think that any child, with the proper nurturance, can blossom into some kind of academic oak tree, tall and proud. It's just not so.
Multiple intelligences provides a kind of cover to preserve that fable. "OK, little Jimmie may not be a rocket scientist, but he can dance real well. Shouldn't that count equally in school and life?" No. The great dancers of the Pleistocene foxtrotted their way into the stomach of a saber-tooth tiger.
That is the root of the matter. Too many people have chosen to believe in what they wish to be true rather than in what is true.