I'm in favor of phone-free schools, but trying to ban things smart phones for under 14s is dumb. Our young peopole need more freedom not less. 

and practically speaking trying to enforce a social media prohibition on under 16s would be a useless embarrassing fiasco. 

Further the message it sends is insulting to young people. They'll all hear "You're too stupid to handle looking at Facebook" which is exactly the same degrading treatment that caused their giant mental health crisis in the first place.