For some context, messenger (originally FB chat) didn't launch until 2008. A year later in 2009 FB started sorting posts by popularity, by 2011 they'd switched the newsfeed to a blogspam / advertising feed, burying your friends posts. Depending on your age, you may never have used 'golden age' Facebook. As someone who was in college 2003 - 2008, there was a period in which Facebook was an insanely useful tool for organising your social life. You could literally make a facebook post about an event or even stating where you were on a given night, and know that people were likely to see it.

Facebooks business model after around 2011 explicitly became disconnecting people. This isn't stated loudly enough or often enough, but algorithmic feeds and mixing 'news' 'entertainment' with real status updates meant that social networks in general became forces for disconnection and polarisation around this time.

Early FB and Twitter were useful and operated in precisely the opposite way - because they didn't use any algorithmic filtering whatsoever.