It doesn't have to be national threat. Social media can be used by small organisations or even sufficiently motivated individuals to easily spread lies and slanders against individuals or group and it's close to impossible to prevent (I've been fighting some trolls threatening a group of friends on Facebook lately, and I can attest how much the algorithm favor hate speach over reason)

That's a non sequitur. Your personal troubles are irrelevant when it comes to public policy, social media, and the fundamental human right of free expression. While I deplore hate speech, it's existence doesn't justify censorship.