Agree with most of this, but I'm curious where Facebook groups fit in here. We recently moved to Florida and have been scrambling to find non-religious home school friends for our daughter (homeschooling because of Covid). Facebook has been pretty much only resource available, and I've joined a number of local groups that have proved somewhat helpful. I'm wondering whether groups may provide a level of stickiness and user retention that the timeline may not?
Facebook Groups and Marketplace are both good examples of content graphs. Your social network is irrelevant to them, in fact you may prefer NOT to see the listings made by your friends/family as the negotiation/purchasing is often nicer when it is relatively anonymous. Facebook's one moat is very shallow in this space.
Unlike high attention media with placement and interstitial opportunities, Marketplace and Groups are not great business models.
The social network graphs of the people contributing to e.g. a local group or marketplace helps in making sure that people behave somewhat honestly, I've found. At least in locales with like < 5k people.
