It's terrible because it teaches everything in isolation. You have a section for this tag, a section for this function, on and on. You never get a feel for how

It's terrible because it teaches everything in isolation. You have a section for this tag, a section for this function, on and on. You never get a feel for how all the pieces fit together to build something non-trivial. It's only useful as a reference. And even for that purpose its terrible because the information density is way too low.