CBC radio had an interesting interview with Franklin Foer this past weekend. He makes that argument during the interview and presumably in his book World Without Mind.
Well there are a couple of studies that track vitals and responses of people who get their cellphones taken away. So it's not like that's an empty implication.
What about taking away peoples ability to go out with other? Looking at “cellphones” as one collective thing is foolish, it’s a platform on which all of modern life takes place- you’re causing them serious harm by taking away their phone