Almost all education (think math) is taught in a linear fashion, teachers teach in an order because they exist in linear time, and textbooks are organized front to back, but learning should be more like a DAG (a tree) of dependencies.

We don't even need AI. I'd love to see something like Khan Academy mixed with space repetition and an DAG of knowledge dependencies. If you get a question wrong, the spaced repetition algorithm should present material about the underlying dependencies. Unfortunately, Khan Academy is focused on conforming to the linear paths (curriculums) that schools and universities have chosen.