Because wisdom (and, more to the point, advice and mentoring) is highly context-dependent. It depends not only on your current understanding of the material, w

Because wisdom (and, more to the point, advice and mentoring) is highly context-dependent. It depends not only on your current understanding of the material, which software has trouble measuring anyway, but also on the way you are thinking about the particular problem and the types of related subjects you have worked with. Not to mention your life situation and overall attitude at the time. A good teacher can take all these into account, deciding when to challenge a student versus focus on reinforcement, pulling in examples from related material with which the student might be familiar, etc. Software-based learning might work for the subset of people and subjects which can be commonly learned from textbooks by self-motivated individuals now: things like programming, math, some science. But many people require the social interaction, and many topics cannot be easily managed in a purely information-dump approach.