The bigger question may be why do we even still have "textbooks," at least in their traditional form? Are textbooks the optimal way to learn given all the technology we have today? I'm sure there are quite a few start-ups working on this problem.
I'd have to say there is a good use case for textbooks in engineering. Go into any mechanical engineer or chemical engineers cubical and you will find that they all have many of their college textbooks. Textbook chapters are a way better organized than websites when you are looking up values in tables, applying them to equations, and adapting example problems.
That's not anything that couldn't be solved with a better designed informational website or app. Those textbooks persist only because someone's making a lot of money from making them required parts of a course.
That's the main issue, textbooks are not the ideal form of learning for some subjects.
Studies have shown that text is not the ideal format for novices to learn a subject for the first time.
I'm a co-founder at https://www.clutchprep.com and that's what we're tackling. Students go to 300+ student classrooms, don't learn much and then have to rely on a $250 textbook to teach themselves (doesn't work well for most). It's a broken system.
I think it's pretty hard to find something more efficient than sitting down and reading a textbook and doing the exercises to learn something you actually want to learn.
For software related jobs, pretty soon I'm going to start accepting candidates with substantial coursera credits. Furthermore, we'll be looking at courses in related fields.... Epidemiological Modeling in our case. Students who have successfully completed those core courses and have gained actual knowledge will easily come through in the interviews.