This would be reason enough, but they are actually starting to rely on them as a way out from the company they are in. It allows them to opt out from conversations they don’t like or can’t contribute to. It has become the ultimate social prop. Previously the only available social props were cigarettes and alcohol, but they helped social cohesion, not hindered it. (I’m not saying they are better but it’s interesting to see what technology has created and how it is affecting human interaction.)