I do agree that dismissing classroom and on-land education out of hand is going much too far. I've said it before, that I believe there are different kinds of learners, and although the kinesthetic learner will do best with hands-on corrections during execution, visual and auditory learners may do better with more lecture or more video. I have found video feedback to be one of the most valuable things anyone has done in my diving classes. SEEING what I am doing, and being able to correlate it with my own proprioceptive information, has helped make faster, bigger changes than being tapped on body parts or doing land simulation drills.
But I will totally agree with this statement: I worked with my Fundamentals instructor for a year and a half after my class. I took a second class, Rec Triox, from him, and I just could not pass the thing. My buddy and I went out time after time for reevaluations (all done at no charge, so there was no profit motive in holding us back) and just couldn't quite reach the bar. I eventually went off and took some "diving lessons" from a different instructor. My Fundies teacher subsequently contacted me in what I still think was an amazing e-mail: He said, "I have given you feedback in your classes on how you have done and what you could improve; now I'm asking you to do the same thing for me." He wanted to know why I had changed instructors. And I told him -- he was very good at telling me the "what", and showing me where I didn't manage it, but he wasn't helping me with the "how", and I just wasn't having any luck figuring it out on my own. Practicing diligently does not result in improvement, if the same mistakes are being made repeatedly.
The new instructor helped me a great deal with the "how". For example, he immediately spotted the fact that, when I got things out of my left pocket, or reached for my left-hand valve, I rolled my body to the right and vented my dry suit -- this resulted in buoyancy problems I'd have to fuss with in the middle of the drill. Just learning to inhibit that roll got rid of a ton of instability.
I think a lot of instruction is about the what. I would like to be better in helping the students I work with with the how.