Kids who are behind, even if they get the majority of teacher attention, still suffer, because in an appropriately tracked classroom all the teacher's efforts w

Kids who are behind, even if they get the majority of teacher attention, still suffer, because in an appropriately tracked classroom all the teacher's efforts would be targeted toward them (and targeted toward getting them to step n+1, not putting heroic efforts into getting them to step n+2). But broadly we're in agreement, and the resistance you mention speaks to a broader, uncomfortable-to-discuss issue with the priorities educators have.