But let's take bad effect down a notch, from a crime to just an unpleasant consequence if you want. Let's say instead of getting doxxed and physically threatened, you just get turned down for a job offer instead. What about that?
Any “fact-checker” is going to have the problem of needing to arbitrate truth, depending on your arbiter you can have lots of different truths. You include facts that help your case, and ignore or downplay facts that do not help your opinion.
You would potentially have legal recourse against the author, and the platform if they didn't act on you reporting the content. I don't know how that would apply were the author in another jurisdiction/country. I don't know if it's universal, but in Australia you'd request identifying information (IP and timestamp) from the platform via lawyer or police, they'd comply and remove the post if appropriate, and then you'd take the information to the owning ISP, get more detailed information and take the author to court.
I would guess that if the content were brought to the platform's attention and they didn't act reasonably, you may have recourse against them.
The debate here as I understand it is about not illegal but misleading, distasteful, harassing behaviour.
With my forum, I ask the disgruntled user to have their lawyer contact me as a form of pre-action discovery. That weeds out the ones complaining without a leg to stand on and gives me a little bit of protection. The timestamp and IP address (at least with Australian ISPs) is rarely a slamdunk, and it pushes the real judgement on ISPs who have established systems, and police.
BTW, this is just incredible: "An Economist/YouGov poll in late December 2016 found that 46 percent of Trump voters and 17 percent of Clinton voters thought Pizzagate was real."
This has nothing to do with any real person, but is just a hypothetical situation pertaining to this question in your post:
Let's say an account X with many followers calls you a pedophile. You're not, of course, so you responded and said you weren't, but since the followers tend to like X, they don't listen to you. X's followers then dox you, find your address, and start making threats to you outside of the realm of social media.
Does the model of "the people decide what is wrong and what is right, what is true and what is false, what is fact is and what is fiction" hold up here?