Your criticisms are of the submission's design, not the idea. I don't think that this submission fully emphasizes the advantages of a dynamic, interactive document as a medium for conveying ideas. I think this does it much, much better:
http://worrydream.com/LadderOfAbstraction/
https://news.ycombinator.com/item?id=3099595
see also: Khan Academy
Your criticisms are of the submission's design, not the idea. I don't think that this submission fully emphasizes the advantages of a dynamic, interactive document as a medium for conveying ideas. I think this does it much, much better:
http://worrydream.com/LadderOfAbstraction/
https://news.ycombinator.com/item?id=3099595
see also: Khan Academy