Effectively, the education establishment has not really thought through their entire paradigm, and it lacks and does not account for observed phenomena. In science, their hypothesis' and theories would be rejected outright.
They stopped thinking about it after Piaget. Our whole education system (UK/US) is based on the idea that there are fixed biological stages of development. Whereas educational theorists like Montessori and Vygotsky (with his Zone of Proximal Development theory) believe that with independence / support children can move quickly from their current level of ability to a higher one. How? By keeping work sensibly challenging, and giving the necessary scaffolds for the child to meet that challenge. You should check out Tools of the Mind (good elaboration on Vygotsky's theories, click the link for an article about the book
http://www.nytimes.com/2009/09/27/magazine/27tools-t.html?_r=3&pagewanted=1) and How Children Learn: From Montessori to Vygotsky - Educational Theories and Approaches Made Easy, for more on the ideologies that influence popular attitudes towards early learning.