There are a surprising number of huge names with zero presence in the Twitterverse or other platforms. Just this week, Harper's Bazaar cover star Jennifer Aniston opened up about her aversion to social media. "We work so hard to maintain some sort of life and privacy, why would we intentionally put ourselves out there?" The woman's got a point. Privacy is one of the most commonly cited reasons that actors like Emma Stone and Bradley Cooper say no to social media. Others, like Emily Blunt, say it's too much upkeep. (Heard that!) George Clooney, for one, thinks it's asking for trouble — and based on the never-ending cycle of celebrity Twitter beefs , Clooney hit the nail on the head.