A lot of the misinformation in 2016 came from scammers in (I think) Madagascar driving traffic to adfarm blogs with nonsense via FB. They leveraged FB's engagement algorithms to spread viral misinformation to drive traffic. They tried lies targeting the left and the right, but the lies targeting the right spread more easily so they focused attention there.

FB's engagement algorithms leverage confirmation bias in an attempt to spread things the most. I don't think they set out to do this necessarily, but if you measure viral spread and optimize for it - this is what you get.

With political ads, focused targeting at scale is a new type of very effective manipulation that's had a large amount of intellectual capital poured into it. I think it's worth special consideration when considering its effect/risk.

Steven Levy's book was a great (and fair) read on this: https://www.penguinrandomhouse.com/books/551043/facebook-by-...