One of the issues in my area is that there is increasingly nothing else for kids to do. Youth centres are run on a shoestring or closed down entirely, parks react to groups of loitering kids as if they're criminals, and malls don't want them there unless they're going to buy something.
I suspect that a certain amount of why kids use social media is that it's a refuge: there is nowhere else for them to go to socialise with people their own age.