When you are viewed as a subject matter expert in a certain category, you are elevated to a position of authority. People will come to you and seek you out for advice and ideas on how to use your knowledge and implement it in their own lives.
What does the guy who performs with his musical trio at your local coffee shop have in common with the lead singer from a Top 40 pop band? What does the woman who runs the local theater in schools program have in common with an Academy Award winning actress? What do all of these people have in common with a popular local lawyer, doctor, or teacher? They are all people who have to communicate consistently with a wide variety of other people.