I'm puzzled by your comment "At least now, with PADI, the instructor is supposed to demonstrate all of the skills then let the DMC practice". It's always been that way as long as I've been an Instructor. How else are they supposed to learn?
As recently as the 2010 Instructor Manual, it did not state that the instructor had to demonstrate the skills for the candidates. I don't know about 2011, but the 2012 Instructor Manual specifically states that the instructor is to demonstrate all of the skills for the candidates as part of the conduct of the exercise.
I learned all of the skills in my Open Water class. For my DM, there was never an instructor demonstration of the skills. I was told to re-watch the OW video for the skills. While I'd like to think that I was that good that I wouldn't benefit from the demonstration, I know that isn't the truth.