Why? Because algorithms.
Maybe "censorship" is a strong word in this instance — do we prefer "selective disclosure"?
Regardless, not what I signed up for. Deleted FB.
It's also possible that Facebook determined that this person has substantially different politics than you, and has put you in different 'boxes'. You can actually check what groups Facebook thinks you belong in. For instance, Facebook thinks my peer group is 'Starting Adult Life', and my US Political Stance is 'very liberal'.
(Facebook also thinks I work in a production occupation, like mining, or lumber, which couldn't be further from the truth, which explains all the ads for industrial equipment)
I went to high school in a really conservative place, and I'm friends with a lot of people who have wildly different views on religion and politics. A few years ago I stopped seeing their posts, even if I added them to the group of people I see first on Facebook. Meanwhile, I started seeing a ton of posts from people who I barely knew in college, presumably because their 'beliefs' were much closer to mine.
I'm extremely cynical, and I find dogmatic people of similar beliefs as annoying as people whose beliefs I disagree with, and my Facebook feed became a personal hell of dogmatism, especially leading up to the 2016 election. As a result I check Facebook at most once a week. It's entirely possible that leaving the platform improved the experience for some of my more conservative peers from high school, who no longer have to see my posts on the walls of mutual friends.
Apparently I'm 'very conservative'... probably because of my friend group, since I've never posted anything political on Facebook.
The four groups I’m in are all related to using a mobile device or wi-fi.
I’m pleasantly surprised but it appears deleting all of my content, unfollowing every person on my feed, not logging in except on incognito windows and very infrequently at best, and using ad blockers has effectively stymied facebook’s ability to establish a good notion of who I am beyond the most extreme basics.
I still use messenger although I try to use encrypted messages when I can, but they don’t mine that for advertising information according to their user policy. Not sure if they mine it for anything else.
Either way, good.
Honestly though, as William Wrigley Jr once wrote, "When two men always agree, one of them is unnecessary." I have one friend that I disagree with about literally everything, and I respect him a lot because every discussion we have is thoughtful, and my ideas and beliefs are better for having discussed them with him.
Anyways, your political bent is probably based on what types of posts you've read or liked, or even who has liked your comments, even if they were apolitical.
https://www.facebook.com/ads/preferences
And then open Your Information > Your Categories. I assume this is what they are talking about.