I would be interested to see how a self paced learning program with a dedicated teacher would end up if it was focused on embracing getting sidetracked. I know I've sat through history classes in the past and had semi-unrelated questions I wanted to research or ask about but didn't want to waste people's time. In situations like that I would prefer to have a computer to get a quick answer versus pondering it in the back of my head.
There must be some truth to an idea that you don't learn as much from an answer from a question you didn't ask.