That a spectrum of methods is needed to deal with a continuum of student needs is not in dispute. But that you can draw a dividing line most surely is. That line creates substantial minorities in each group who are inadequately provided for in the generality of this dualism.
But this dualism is not unique to him, far from it, as Zeno points out it permeates the entirety of the educational system and has done so for years. It is the problem of Weberian ‘Ideal typologies’ generally true to some extent of most, atypical of some, and with an inbuilt tendency to generalize the uniqueness of the ideal..