Big difference between the clickbaity verson on BoingBoing (“Everything you know about teenage brains is bullshit“) and the dry, academic version on cell.com:

[C]urrent evidence suggests that typical Internet activities do not impair social development during adolescence. | Both adolescents and adults are now using the Internet more than ever. Evidence increasingly suggests that time spent online does not displace time spent doing other activities associated with health and well-being. Indeed, a recent longitudinal study of 14–24-year-olds (n = 719) found a positive relationship between moderate Internet use and participation in ‘real-world’ activities such as sports and clubs. —.