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.