Banning social media will never work, just as banning prostitution, drugs cigarettes and gambling don't work (in a broad scale). What we can do is change the public (and our) perception of it. Understanding you have a problem is always the first step in any N-step program for whatever addictive substance. Most adults don't see their own consumption and behaviour around social media as harmful or problematic or simply deny they have a problem - just as is the case with any other substance. That is where we have to start. Once we (as in we as society) start agreeing that social media on average (!) is harmful, the narrative shifts. Right now parents don't think they do anything wrong by giving a 10year old a smartphone unsupervised. Everybody in society would look condascending on the parents if they hand out cigarettes to a 10yo child - probably even calling the cops. THAT is the sentiment in society where we need to be. It starts with us adults condemning social media use first, else all attempts to outlaw or ban it will fail.
Looks like the study refers to banning cigarettes for young adults under age 21. I was referring to a complete ban, all age groups. I doubt it will have a big impact on actual smokers, but similar effects as we saw in the 1920s alcohol prohibition. And I would imagine that a total ban would get actually more young adults to smoke (because it is illegal anyway, and dealers dont care for age verification).