The article addresses this. Unfortunately the "teachers" were being paid mostly just to be strong opponents for the "students". So AI ruins their market. From

The article addresses this. Unfortunately the "teachers" were being paid mostly just to be strong opponents for the "students". So AI ruins their market. From the article: "the Go school recruits a professional player, who would agree to play a fixed number of games, like five games, one per week, at a certain price.... Of course there is still room for lower level classes and teaching, but pros are often better at playing teaching games than explaining easy concepts."