Books are important in learning. There the main mode that we base things off of when learning or teaching but there are also other modes are learing that make it eaisier for some people to learn. I think that you need a variety of modes to learn everything fully. Along with a book its also important that you get involved with what your doing. If you did a project on what you are studying or go to the many resources on line you could learn a lot and possibly more than what is in your book because people are discovering more and more information that is put on the internet but not put in books.
I think Micky is right. The more learning avenues a person uses and the more of the five senses he/she uses, the better the learning will be.
Books allow us to review what others before have thought on a subject. We can analyze the past thinkers.
Yes, this same can be passed orally or learned (sometimes) through experience, such as fire starting, but books make it easier, and save time. If you want to start a fire with sticks, it saves a lot of trial and error to look it up in a book first.
I learned winemaking through books first, and experience fine tuned it. Yes, I can pass that experience to others, but the basics are fundamental, and they are in books. Remember what happened to civilization when the Greek and Roman libraries were burned..civilization lost 400 years going through the dark ages.