This is interesting, and somehow I don't doubt the results. Much like assuming absolute responsibility for your place in life is beneficial on an individual level yet can lead to problems when applied to society at large, perhaps the existence of smartphones and social media is anxiety inducing for society as a whole, yet the rational individual choice is still to participate, so as not to get ostracized and miss out on social engagement. We can't compare results with a counterfactual society, but maybe polling students at schools with no phone policies vs students elsewhere could provide some insight.