It’s a lovely product and you can tell a lot of work went into making this course. But I fail to understand the author’s logic behind “a good course has to be free”. Why though? What’s wrong with creating value (like The OP) and then extracting it from the people that benefit from it?

In fact, there’s tons of anecdotal evidence that free MOOCS haven’t faired well in terms of retention precisely because of a lack of a buy-in from the people taking those courses.