"But @bjt2n3904, misinformation is bring spread, that is causing 'real harm' (TM)!" Some justification. Real harm is being done now, and it isn't doesn't need social media to survive.
You know, I spoke out against online platforms taking responsibility for what it's users wrote back then. But I wish I had the forethought to say this:
How do you think conspiracy theorists, who believe their messages are being suppressed to hide the truth, will react when Facebook steps in and fulfills their prophecy?
How do you think people who don't live in the tech bubble will react when they share an opinion on politics, and it gets marked as "Actually this is untrue" by Facebook, and buried?
How do you think people, who already believe everything they read on the internet, will react when they see Facebook flag something as "untrue"? Certainly, it won't reinforce their biases about how <political opponent's supporters> are all misinformed people with the wool pulled over their eyes, and can be dismissed off hand.
Surprising to no one, these attempts at correcting "misinformation" are having the opposite effect. Who would have thought that using technology to solve an obviously human problem wouldn't have worked?
Edit: "Ackshually, @bjt2n3904, Facebook isn't under any obligation to follow the 1st Amendment, there's this great XKCD comic that explains this, hold on..."
This is what we mean when we say "freedom of speech". It isn't just a good thing for the government, it's good for society, too.