There should be standards, even if they aren't defined by law. "The Protocols of the Elders of Zion" was republished by Henry Ford as part of a series of anti-semitic articles. The decision to publish them was immoral and is evidence of Ford's racism. I'm sure employers at the Economist would be angry if it started to run articles that would be a better fit for the National Enquirer.

Facebook is kind of different, it argues that it's a platform not a publisher. They do have some ground to argue for looser guidelines. But their business model targeting engagement incentivises them to promote divisive and false information. I'd be much more comfortable with Facebook if they didn't promote extreme and dangerous content. What those standards should be is a thorny issue, but better moderation would be an improvement.