Bad User Interface
What do I want in a social network:
- Ability to customize what I see: who and topics.
- Ability to customize what I share, how it looks, and who sees.
- Competent searching, organization, and management of my stuff
- Competent feedback
Facebook fails at all that that. It doesn't give me control of the layout, easy management of people and what they see, what and who I get to see. Searching is shit, there's no grouping or reference for what I make available, and if I don't like something, I can't even put a thumbs down.
Each of these decisions has a reason, but they're wrong. Individually, they may increase stickiness, or prevent things like too many dislikes which might make them post less or resist the platform. But what the dimwitted geniuses miss, is that holds true for A|B testing of a feature in the short term, but not over time. Users will not put a dislike and that prevents the the recipient from getting their feelings hurt -- but then that also prevents them from growing. And the annoyed reader may go ahead and comment, which hurts the feelings more -- and may result in either side blocking the other. They prevented short term usage decrease, by increasing the odds of long term ones.
The most basic features like browsing everything you posted, is hard. The ability to auto-purge your posts after time. You do something simple like blocking someone, they remain in messenger panel. I turn off notifications, or unfollow someone, I still get notified.
In 2015 an Intern Candidate stupidly pointed out a security flaw in FB Messenger that he'd been trying to get them to fix for 3 years, and was fired (uninvited) for being public about it. Don't get me wrong, the kid was an idiot to spit on the company that had just hired him. But FB was more stupid to have not fixed the bug, and lost the PR war by hiring him without fixing the bug first, or working with him to mitigate the damage and remedy the problem. Though, if he could do that much damage from the outside, I'm not sure I would have wanted him inside the fold either.
The point is either you believe that the politburo knows more than users, or you trust users to manage their own relationships.
There's a bazillion meme's out there, all hinting at the problem. Either Mark is right and the world is wrong, or Mark is pissing off his base, and to egocentric to recognize that he's failing as a good leader.
There's two ways to lead. (1) Annoys a few people (2) Annoys most people. I'd guess that Mark is firmly in the latter category. Which is fine, you can be successful in spite of yourself, just not as successful as if you had the maturity and likability of the average 30 year old.
Here's a few links on their anti-conservative bias.
- They work with the far-left hate-group called SPLC and use that highly biased source to flag what is FakeNews or not. I guess ThinkProgress and HillaryForPresident.org was too busy and unbiased for them.
- Facebook's political contributions (by party) is about 2:1 for Democrats (even when Republicans are running things), that's better than the 100:0% split for the first few years. 
- 2018.03.14 - FB Bans Britain First for being anti-immigration or "right wing". They claim for violating vague speech codes, but they do not lay out a case for it (other than Trump retweeted videos that seem to accurately claim that Muslim mob threw a kid off the roof and beat him, or stuff that the left claims is hate speech to expose). If they showed objective standards, and how the terms were violated, I might be sympathetic. (Or if they were banning those that retweeted CNN videos that were inflammatory against the right or gun owners), then maybe they'd have a moral position. But inferring that anti-immigration is the same as hate speech (while ignoring hate speech against conservatives/gun owners), and not being able to back it up with details, is just incompetence/bias, masquerading as snowflakes version of tolerance. 
- 2016.05 - There are multiple employees that admit they "routinely suppress conservative views" 
- 2016.01 - Israel Project did an experiment where they showed equally offensive anti-Israel and anti-Palestine videos, and of course the anti-Palestine one was taken down. Only after it caused a stink, did Facebook take down the anti-Israel one. Now no one would confuse something called Israel Project with an unbiased source. But their evidence was pretty obvious. They later pulled the story and examples. No one is sure why, but FB demonetizing or deleting conservative pages they don't like is a pretty strong hint. Whether that was through direct threats, or just Israel Project seeing the writing on the walls, doesn't change the point. 
- 2014.02 - If you want to see if they're stupid-left, to what absurd degrees they'll go to appease the intersectional marxist, you need look no further than their 57 genders -- which confuse sexual preference with gender . Physical gender isn't that hard. Male (XY), Female (XX), Both (XXY, XYY). Done. The rest is sexual preference. While I think people's uniqueness should be respected, FB proved they're close-minded by only using the sexual preferences as seen by SF/Seattle LBGT communities instead of being fully inclusive and adding in: experimenting, drunken mistake, glory-holer, Frotteurist, Pederast, Objektophilie, Necrophiliac, Coprophagiac, Beastiality (each animal or group should be called out), Celibate, Banjee, Voyeur, Exhibitionist, autoerotic asphyxiation, crush videos, and so on. The point is, I don't care. You can do whatever you want to among consenting adults, but your kink isn't your gender. And if you're dumb enough to think it is, then list all possibilities, instead of the politically correct subset and pretend that's tolerance.
Facebook bought Instagram, so what they do, Facebook does. And Instagram withholds likes from people, to get them to post more often.
Support of criminality
I have some second hand knowledge of FB doing what they can to dick with law enforcement (back in 2010), who had government granted warrants to go after pedophiles, stalkers and other abusers. I don't know if that came from the top, or the middle, but they were endangering people's lives by giving LEO's (Law Enforcement Officers) the run-around. But warrants can go too far, and not sure secret warrants are tolerable.
- Intern firing: https://medium.com/faith-and-future/stalking-your-friends-with-facebook-messenger-9da8820bd27d
- Facebook Political Contributions: https://www.opensecrets.org/orgs/totals.php?id=D000033563
- Suppression: http://gizmodo.com/former-facebook-workers-we-routinely-suppressed-conser-1775461006
- Israel Project:
- 57 genders: http://www.slate.com/blogs/future_tense/2014/02/13/facebook_custom_gender_options_here_are_all_56_custom_options.html
- Instagram: https://twitter.com/AndreaCoravos/status/951894779570376704/photo/1
- Refuses to give "unlike": http://techcrunch.com/2009/02/09/facebook-activates-like-button-friendfeed-tires-of-sincere-flattery/
- It decides what friends you want to follow or not: http://dangerousminds.net/comments/facebook_i_want_my_friends_back
- Suffocating under it's own weight: http://www.businessinsider.com/facebook-news-feed-benedict-evans-2013-12#ixzz2nkbqsNL1
- 2014 - Princeton wrote a paper predicting Facebook would lose 80% of its users by 2017. The paper was criticized and it did happen by 2017, but there has been a significant slowing of new user acquisition and a noticeable drop in usage in the last couple years. So not quite the doom and gloom predicted, but there is a stagnating effect.
- I looked back at comments I made in 2014 in response to the paper and explained for FB to die, there would need to be something better and Twitter and GooglePlus wasn't it.
- There were some alternative sites that were started (like Gab) to try to combat Facebooks censorship, but if there are a few asshats on a free speech site like Gab, Google and others will attack/block them as racist solution, when it's really a free speech solution (which attracts all kinds, including a few racists): https://en.wikipedia.org/wiki/Gab_(social_network)
A drop of goodness? - not everything they do is bad.
- 2017 - While FB has done a lousy job of FakeNews filtering (and what they filter is just conservative truths they don't like), but then they do some good by fighitng even further left governments (like Germany) who want to decide what people can see/read, in the name of marxist fascism: http://www.independent.co.uk/news/business/news/facebook-germany-fake-news-law-tech-companies-delete-legal-content-social-media-hate-speech-fine-a7763081.html
- 2012 - Eduardo Saverin, Argentinean billionaire co-founder of Facebook Inc., renounced his U.S. citizenship to save hundreds of millions on his taxes when Facebook IPO'd: https://www.bloomberg.com/news/articles/2012-05-11/facebook-co-founder-saverin-gives-up-u-s-citizenship-before-ipo