But the bigger problem is that it won't work. They'll just set up PoPs in country. The law has never stopped criminals. They are criminals after all, breaking the law is a given.
If it did work a ban would give those countries a big kick up the ### to actually do something about it. Many countries just let it happen because of corruption. Sometimes something is done like recently in Myanmar but it's very rare and usually just for show.
There are obviously a lot of other issues with social media sites like Reddit or HN but imagine how different local community subreddits would be if there was some way to know that the person you're talking to actually has some personal stake in the community and people there.
Personally I'd still want to slum it up on the non-regulated social media sites but I'd post on the pseudo-anonymous community sites and take what others have to say more seriously on there.