I don’t see this as having anything to do with equality or inequality. Brain development just IS. The question is whether you can do anything that changes it. Supposedly that was what education was about before the educational community decided it was better suited for propaganda.
It most certainly does.
If economic and social value of a person is mostly determined by the quality of his brain hardware, then social roles and therefore status are largely fixed and predetermined.
It also opens the nature of education - is the function of education really to put stuff into peoples heads, or is it more of a filter to sort out the people according to the quality of their brains?