That is indeed a good question. One of the key challenge in reforming education field is the feedback cycle is big. Very time consuming to track experiments.
So I have add that what I stated was my hypothesis reinforced with a small dataset of my experience teaching 'Computing & Internet' to middle school kids.
I have to clarify that my comment was targeted towards current Udacity (other MOOC) participants who wants to learn programming as a value added skill or hobby.
If you want to graduate with CS major and/or want to pick CS as a profession; I do believe you need to have a good understanding on the entire stack. There are no shortcuts to being a good professional and achieving mastery in any field requires committed hard work.
I'm happy to live in a post-Alan Kay world, but I think maybe it's time to dust off that sculpture of Dijkstra we keep in storage and move it out into the foyer. Programming is hard; glossing over what makes it hard in the name of doing stuff sooner may or may not help, but as long as we debate it without testing it empirically we're sure to get nowhere.