"I think that for platforms like Twitter and Facebook, perhaps it may make more sense to end up a situation more like newspapers, where you have more reputable papers like the NYT, WaPo, and WSJ that have stricter rules, and then you also have the National Enquirer or other random outlets that have little to no standards."

Don't forget, media outlets can get the pants sued off of them for knowlingly publishing false and defamatory information. I think we're well past the point of websites being held liable for the content they host, user generated or not, and make public/promote algorithmically.