Instead we are saying "only adults should use this" which, while technically regulating the industry, places the restriction on users.
We're treating it like tobacco or alcohol (2 industries who have similarly spent millions upon millions of dollars in lobbying efforts) but we should be treating it like asbestos.
Just because I don't know how to write a law that can prevent it doesn't mean that I can't recognize an actual issue when I see it.
Forcing the users to verify their age changes nothing. It gives the illusion of "doing something" but it just gives facebook data they already had. What's still needed is regulating social media platforms themselves to place explicit limits on what they can do to hurt their users, including children.