Imagine following a group of students from Kindergarten to the end of high school, and you're never able to understand any words spoken or symbols written down, whether mathematical or alphabetical. It would seem to you, at the end of about 12 years, just a swirl of conversational sounds and strange hieroglyphics shared between and among adults and children.
Now imagine that all of this bizarre content—somewhere north of about 10,000 hours of instruction—matters far less than how much money people have or their mental states. Certainly now all of this content seems like an absurd waste of time. Why make so many mouth noises and scribble alien symbols all the time when just being rich or motivated to do well—or any of the hundred other things that don't involve the noises and scribbles—is of more importance?
On the other hand, if you infer that the incomprehensible aural and verbal signals are important—as the behavior of the system seems to imply—then it is reasonable to assume that they affect some outcomes in some way. If, for example, I were to visit a different group of students, engaged in making a significantly different set of noises and scribbles, then I should expect to see something significantly different about the two groups, provided I know what I'm looking for, both in the way of content differences and outcome differences.
But Does the Behavior Match the Belief?
While almost everyone would say that the content of instructional discourse is important, it's difficult to find a sizeable gathering of people who behave as though this was true. That is, if you happen to sojourn outside the classroom during your longitudinal stretch as an alien observer, it's safe to say that the scribbles and noises you would encounter there would overlap very little with those inside the classroom, even if you follow practitioners, communicating about the classroom.
Although I think that much about this has improved in education in the last 20 years—my sense is that Common Core has made collective work on instruction easier—the general character of the system is still that of managing children in classrooms rather than working on instructional problems.
Classroom management is, at the moment, the dark matter of the instructional universe. If your excellent theory doesn't account for it, it won't work. I'm not sure this is anything to celebrate or be proud of, though. Quite the contrary.