Imagine you know a young boy who's very interested in butterflies. He wants to collect them, study them. He wants to be an entomologist and study butterflies all day. Now, imagine you tell this boy that the best way to learn about butterflies is to go out and collect them. Just keep looking. The boy trusts you, and goes out and collects butterflies. He comes to know a great deal about what butterflies look like. But he doesn't know the names of the parts, or that males and females are the same species even when they don't look alike. He might not even realize that butterflies start as caterpillars, because he's only been collecting butterflies.
Imagine you told the same boy instead to read about butterflies while he was collecting them. Imagine you gave him a book that you trusted, and let him match up what he saw when he collected butterflies to what was in the book. Now he not only knows what the butterflies in his collection look like and how they move, but can also describe how their parts fit together and how they can fly.
For some people, books are like those butterflies. We can read all we want, but we will never intuitively put together why things work the way they do, or if we do it will be only after spending ten years reading and nothing else. We will never figure out on our own why our books don't work. But once we read a good book or two about why good books work, we can match that information to the books on our shelves and the ones coming out of our fingertips.
On the other hand, it's far too easy to become lost in the sea of how-to books and not do the work of reading and writing. And in the end, if you want to learn about butterflies, you're going to need a net.