Although I am a firm believer of the above, I do not believe that Governments are doing it because they do care about our health. Quite the opposite. I believe they want to manipulate us as much as they can so they can keep in power.
Although they want that, they have seen that social media has the power on gathering people and creating protests, so I believe they want to cut it off on younger people that usually have way more anger and got much less to lose (nowadays that the light at the end of the tunnel is fading) than a middle-aged man being mind-controlled his whole life being a good abiding citizen.
Its a power tool, they are just swinging it where they want. Soonish in EU we'll have the same ban, but it won't be because EU politicians cares about children, it is so they can keep their power and not have a generation that has access to other sources than traditional media and structured schools grooming them on just obeing their masters.