[mrob]

More authoritarianism from the UK government. A more reasonable solution would be to make it illegal for under-16s to possess mobile devices (anything with a touchscreen and wireless networking that's designed to run off battery) and make it illegal to supply mobile devices to them. The problem is ubiquitous always-on access to social networks, not social networks in general. If it's something you have to consciously make an effort to access, like in the dial-up networking era, people won't feel pressured to be permanently online and existing offline social mechanisms will be able to moderate behavior.

It is less authoritarian to regulate property than it is to regulate communication. If there is a genuine problem, a non-authoritarian government must apply the minimum level of force necessary to solve it. Jumping straight to suppressing freedom of speech without trying less invasive solutions is pure authoritarianism.