The users will be less happy - hell, some will be downright miserable - but they'll be more engaged,
You're right. However, users can choose not to participate on Facebook.
Personally, FB is an addressbook. As long as my addressbook can't downvote my ACCOUNT, who cares?
I don't post much and if I post something that I'm interested in and people downvote, I will ask them what's up because they are people I know. If their explanation is sketchy or rude, unfriend. Problem solved.
Good riddance to bad rubbish.
People really need to start growing up and taking their own responsibility regarding their behaviour and mood. If your mood is bad, why is it bad? Are you worn out from running on the FB treadmill of clicking and being possessed by your friends list?
Every human being knows if they are getting sick from toxic things. FB's toxicity is SLOW. It won't kill you right away but it could if the depression or anxiety from whether you will get accepted or not gets bad enough.
Dopamine is what FB is after. It's proven that a 66% negative exposure will double the high you get when you get one upvote or comment.
But FB has had downvote installed for YEARS. It was just internal. If they say they didn't have it then why are so many user posts never seen by ANYONE?
Once the downvote feature is live, the FB feed can go back to realtime posts from all friends. Users could then just lower visibility on friends they care less about.