Stepping back to a larger discussion about censorship, how exactly is "the marketplace of ideas" supposed to fight blatant falsehoods and other propaganda/misin

Stepping back to a larger discussion about censorship, how exactly is "the marketplace of ideas" supposed to fight blatant falsehoods and other propaganda/misinformation? Ignoring it doesn't have the best track record so far, even Mark Twain figured out that a lie can make it halfway around the world before the truth even starts.