Like it or not but it's the twitter that gets value from celebrities. How many people are on social networks jusy so see what their fav celebrites are doing?
The problem for twitter is it isn't the only game in town when it comes to social media, not by a long shot. They're not even in the top ten. They're a megaphone in a large pile of megaphones, and those other megaphones don't bite the hand that picks them up.