It's not the so-called "alt-right" who's responsible for the discrediting the "fact-checking" sites, but those sites themselves. They went overboard with their lies, trying to torpedo Trump's campaign, but instead torpedoes themselves. All "alt-right" did was to expose these lies by using hard evidence.
What happens right now - right after Soros' puppet lost the election, they summoned an emergency meeting to decide how to deal with their growing problem of people falling out of line of their carefully set up lying press. Right after that the press started pushing the "fake news" narrative. After all what happened during the election campaign, you've got to be blind not to see what's going on. They want to introduce heavy censorship to block any attempts to expose the lying press and create a monopoly to report the news. If we allow that, only Jew-controlled media will be allowed to distribute information on the net.