+1. Apparently smaller population do well with text based tutorials, while a larger population needs video based MOOCs to get along with the learning. Pretty much the same reason why schools are still necessary, and self-taught remains a minority in our society.
It's not something falling out of favour with some substitute getting into fashion. It's the inclusion of a larger population into online learning industry. When a majority of the society are compared to the smaller populations that do away with text based learning, you may notice:
(1) Reading disability.
(2) Shortened attention span, especially in mobile age.
(3) Weaker ability to concentrate on material unless being talked to.
It's not something falling out of favour with some substitute getting into fashion. It's the inclusion of a larger population into online learning industry. When a majority of the society are compared to the smaller populations that do away with text based learning, you may notice: