Reading matters. Invention of writing let people preserve and pass knowledge and things that matter through generation. So reading was basically designed to save people from making mistakes someone had already made, to save people from going down the paths, which are already explored. But the obvious reason — to gain knowledge and experience which otherwise would be more expensive to gain — is not the only why lots of media advice so much how you can read one book a week.
Reading can help you to form habit of completion, which is extremely important, because conscientiousness, associated with completion by definition, is the best predictor of many important human outcomes, including mortality, longevity, educational attainment, and a host of criteria related to career success, or at least so stated in «Organized mind».