I appreciate your reasoned response. But the misinformation that we tend to focus on isn't "we faked the moon landing" or "the sky is a layer of impenetrable foil." It's anti-muslim riots in Sri Lanka[1] or the fact that a large percentage of the US electorate believes that the 2020 election was fraudulent. These are clearly cases of "real and demonstrable harm," even if you believe that other things also sometimes cause harm (even if you believe other things cause more harm!).

[1] https://en.wikipedia.org/wiki/Fake_news_coverage_of_Sri_Lank...

Edit: I also wanted to point out that there's a technical term for true information that causes harm, "malinformation." Those of us who have studied misinformation have actually spent a lot of time documenting how misinformation has appropriated the trappings of malinformation in order to become more convincing. Furthermore, most of the misinformation being shared by volume on social media isn't of the "the sky is a layer of impenetrable foil" variety.