The use case is to break some layers of abstraction. If no one would write such a guide, who would create the next OS? We would all be dammed to copy existing c

The use case is to break some layers of abstraction. If no one would write such a guide, who would create the next OS? We would all be dammed to copy existing codes and pray they work. I applaude the author for the effort, in particular using images that can be booted should make it feasible to use these techniques for teaching!!