However, a two-way interactive device like a laptop or Chromebook? Typing homework instead of writing it? Having collaborative tools available to work with others, both in and out of school? Playing with preliminary programming environments? Trying experiments and visualizations? Yes, that can absolutely help.
Just handing a device to every student will not automatically improve education, though; they're not magic. There need to be lesson plans, adapted materials, tools (e.g. for teachers to collaborate with students and students to collaborate with each other), and not just the same lessons ported to turn in homework on a computer. That takes time and effort, but the result will be students much more adapted to a highly tech-integrated society.
(Disclaimer: the above derives from professional experience and observations, but is not a comment made with my professional hat on; not speaking for anyone else here.)
As for the comments on social media: yes, and that's something many of them will do as adults too. Many people are highly social, and hang out with each other online. Some of what they do will be educational and productive, but having a computer doesn't mean it has to be used entirely for education and productivity. Even just posting online provides practice writing and typing, both of which benefit from practice. Some of their time might be spent on random Internet forum sites arguing with each other, which of course will never be a skill they'll make use of as well-adjusted adults like us. But it'll keep kids inside and thus off your lawn.