Thankfully, it is just speculation. From their abstract:

  Virtually no evidence exists to test these theories or 
  establish their relative magnitudes.

PhD programs work on the mentor/apprentice setup, though the apprenticeship usually teaches research methods, not engineering methods. To my mind, the mentor/apprentice setup is great when the apprentices are genuine and dedicated and the mentors are competent and equally dedicated. (And, of course, the numbers line up! Fifty "apprentices" and one mentor is just a class.)

I thoroughly agree with the relative value of your work and your school "work". Grades are a means turned into an end, and the sooner one realizes that the goal is understanding and not recognition the better. (It's convenient that the recognition tends to follow unasked!)