Guess what, you ARE responsible
Where all of this is heading, whether these cases, or Google and Facebook's struggle with "fake news" and objectionable content, is to an obvious conclusion: just like print publishers, you need well trained editorial staff if you're hoping to maintain quality, trust, and avoid lawsuits.
It was never realistic to think that armies of random posters, trolls, and "citizen journalists" would avoid <a href="https://en.m.wikipedia.org/wiki/Sturgeon%27s_law”>Sturgeon's Law.</a> In the days of print or broadcast the barriers to entry filtered out the loons and half-baked theorists because the price of printing a book or filming a TV series was prohibitive.
Now any fool can launch a free website in ten minutes and fill it with unmentionable deck.
Fifteen years ago at an NPR conference about digital it was pointed out that the real power on the Internet was with the gatekeepers, the organizations that were trusted to select and curate information on behalf of end users.
I no longer have an interest in tracking down the truth of sketchy reports. I'm much happier if some large organizations that I trust can do it on my behalf.