When considering how to think about these restrictions, I turn to my 15 year old self back in the 90s and ask him "would you want the government to block you from using IRC, forums, guestbooks, and social web sites?"
His response would have been "go to hell", and he would have figured out a way to get around it anyways. Unless they're actually planning to track one government ID per person in a database, a truly horrifying idea that this project is slippery sloping towards (because if the current design is easily defeatable, then why do it at all?)
Having access to the entire internet, warts and all, as a kid did not ruin my life, it was an escape from the people I did not fit in with in the place I grew up, it taught me about humanity and ultimately led to a successful career for me.
Dave Bohnett, the founder of Geocities, stuck his neck out to protect the LGBT section of the site so that young adults could find a place to have community despite often growing up in places where it was dangerous to be gay, like it was for him when he grew up in a very conservative suburb of Chicago.
I don't think anyone has said more negative stuff about Facebook then I have, and I literally made a platform eager to try to destroy it, but this is not the way to do it. We should be thinking very, very carefully about when we let the government become our parents in scenarios like this when the unintended consequences seem quite likely be enormous and when there's no mechanism for retracting the law once it's implemented and we find out that, surprise surprise, it didn't magically cure depression in young adults.
Social media sites today are nothing like the forums and guestbooks of the 90s. Social media now is highly effective at developing addiction like symptoms as well as driving people to decisive topics and conspiracy theories. It has a measurable effect on teenagers wellbeing and academic performance too.
My bigger concern is the how rather than the why on this topic.