Ben sequences it well:
In his new book, which I review here, Tyler Cowen writes:
Placebo effects can be very powerful and many
supposedly effective medicines do not in fact outperform the placebo.
The sorry truth is that no one has compared modern education to a
placebo. What if we just gave people lots of face-to-face contact and told them they were being educated?
He reluctantly provides the terrifying conclusion: Maybe that's what current methods of education already consist of.