As people, we like to be right. So we're drawn towards people who tell us we are right. Social media lets that take over our lives entirely - we can now live happily without ever hearing an opinion we disagree with. My neighbour and I might live one door from each other yet occupy totally different echo chambers.
I think you see this in the way people view Trump, Brexit and the like. No one's preconceptions are challenged any more.
The friends and co-workers I spend time with in person have a much less diverse set of views than the broader group in my Twitter and Facebook feeds. Literally every person I spend real-world time with is wealthy, educated and liberal. Nobody ever says anything truly upsetting.
From an AI point of view it's much simpler to detect if a post is political in nature
If you understand German you can watch it here (6 min). https://www.youtube.com/watch?v=vSEEDB7ViyQ
("Und bist Du nicht willig, so brauch ich ....Geduld".. :-)
Instead, I’m seeing that they have inflated the number of users and ad impressions. Also, I’m seeing an argument that FB is somehow so powerful, that under $100k of FB ads swung the election (even though the campaigns bought 10s of millions of FB ads too).