>Exercises, quizes and explanations are routine enough that good teachers I know can generate them on the spot.

Every year there are thousands of graduate teacher looking for tools to help them teach better.

>good teachers I know can generate them on the spot

Even the best teacher can't create an interactive multiple choice quiz with automatic marking, tailored to a specific class (or even a specific student) on the spot.

I've been teaching for 20+ years, I have a solid grasp of the pain points.