There are books on learning languages, self-help books, books on crafting, and even books on how to write books. If using a text to teach social media wasn’t effective, you wouldn’t find page after page of social media books on the web when searching ‘social media’ on various search engines.
There is such a multitude of information on social media that’s changing daily and it’s important to use a book that has current information. Along with current, an effective industry professional who is experienced in the topic will make the book more valid.
I also think it’s important to incorporate a book with the actual use of social media because it will help engage the learner. Having a book is a good resource tool that can be used to reference information that may have been forgotten, or even to review something we are uncertain about.
I personally like to have a book because I can highlight while I’m reading, make notes, and use it as a guideline to refer back to when needed.