This strikes me as an academic, ivory-tower argument about what one ought to do if they wish to reach a child to read properly, but it completely misses the point. I don't have enough rep to downvote this answer, but it isn't even worth responding to so many of your misguided points. It works, and the success of this book -- and the premise of this question -- is a testament to that. Any well-meaning parent looking to replicate their success teaching their child a new subject like math would do well to avoid this sort of elitist discouragement.