He has a point, though the way he said it might be a little too grand. Sometimes I feel that I'd like to learn some topic X for school, in enough depth that I can solve problems that appear on exams, while at other times, I wish I could learn X just enough to be dangerous. For this reason I sometimes wish there is one of resource for each of those situations, or as the previous poster called them "constraints". But then I realize that as you divide them up like this, they just don't get popular enough for the author to put in enough work or maintain quality.
Luckily, for the most part, the MOOC scene brings us one type and the other type exists a lot on youtube etc.
I hope I didn't sound too much like the previous poster, but when I read what he said, I realized that I too had the same thought process!