I do believe FB would have run ads about Hitler.

The trouble is it's not just FB. It's the whole internet. The problem isn't that everybody on the internet lies. That would be easy to deal with. The problem is that a very large number of people on the internet lie and people are inclined to believe whatever they see that agrees with opinions they already have. Here's a bizarre sequence of events from UK news in the last few days.

1. A child taken to hospital with suspected pneumonia* had to wait for seven hours to be seen and had to sleep on a pile of coats on the floor as no beds or trolleys were available because the hospital was overstretched.
2. Boris Johnson, in an interview refused to look at or comment on a photograph of the incident and when a journalist tried to show it to him on his phone he took the phone without looking at it and put it in his pocket.
3. The hospital gave a statement confirming the incident and apologising to the parents. Thankfully the little boy had severe flu rather than pneumonia.
4. Substantial backlash in the press led to a conservative spokesman being sent to the hospital where he was met by angry, but peaceful, protesters.
5. An unnamed but official Tory spokesman claimed that an aide had been punched in the face and made that claim to the two main TV channels who ran it without checking. The story moved from the little boy to this alleged incident. Many other media outlets made the same claim with one particularly right wing paper claiming an arrest was made.
6. Video footage of the whole thing revealed that there had been no punch nor anything that could be misconstrued as one and that the Tory office had merely invited the incident to divert away from the story of the child in the hospital. This has been admitted.
7. Red-faced TV station and newspaper editors retracted the story.

Now is where it gets interesting and relevant.

8. A number of almost identically worded tweets started appearing claiming to know people at the hospital who claimed the whole incident was staged by the child's parents. (Remember the senior hospital staff had already confirmed that it was true and apologised.)
9.Huge numbers of people who wanted to believe that there is a conspiracy of radical lefties decided to believe these anonymous tweets rather than the statement BY THE HOSPITAL an d retweeted it.

10. I heard a guy phoning in to a radio station say that he didn't believe the original reports, he didn't believe the parents, he didn't believe the hospital's own official statement. It was all a left wing conspiracy and he believed the anonymous tweets. When pressed for his reasoning he said "because it makes more sense to me". That phrase is chilling. What it actually means is that he is willing to believe anything at all as long as it agrees with his own biases regardless of provenance and disregard anything that he doesn't want to think is true no matter how solid the source for that information is.

The internet echo chamber just makes sure that that kind of thinking is everywhere. Brexit is a perfect example and over in America there are still people who, for example, claim Sandy Hook didn't happen because it says so in the internet.

FB isn't the problem. People's propensity for only believing things they already agree with is the problem.

OMG! That sounds like something that would happen here. What is happening to our world? I thought it was just our country.