I think this piece would be more effective, or at least somewhat effective, if its author had described a vision for online learning that takes the best of Khan's approach and combines it with, well, something interesting. The author never really explains what that something is. I don't think Khan Academy is perfect. Its gamification techniques will not work for all students. But it is an alternative for some students. If a kid who is ahead can stay with her peers at the same grade level while watching Khan videos at night, great. If a kid who is behind can stay with her grade level by using Khan to catch up without the shame of remedial math, even better.
Unfortunately all evidence so far seems to indicate that online approaches to learning, on average, do not work very well. To be clear, meta-analyses continue to reveal that schooling, as it exists now, works as well or better than tech centered or online education. I do not find this surprising, if you do not change the philosophy and pedagogy, no repackaging will overcome the serious inherent flaws in the approach. This is particularly pronounced in math Ed and I encourage anyone to dig into the research on what good teaching and learning of math is characterized by.
You wrote "...online approaches to learning, on average, do not work very well..."
Huh? Listen my good man, we aren't talking about the average online approach to learning, we're talking specifically about Khan Academy approach. And I know Khan Academy works for some kids because I've seen some kids using, and liking it -- both kids ahead of their peers and kids behind them.
Whether it works for all kids, on average, is totally irrelevant.
Frankly its author sounds bitter.