For all of Zuckerberg’s EQ, Facebook runs on a very stiff, crude model of what people are like. It herds everybody — friends, co-workers, romantic partners, that guy who lived on your block but moved away after fifth grade — into the same big room. It smooshes together your work self and your home self, your past self and your present self, into a single generic extruded product. It suspends the natural process by which old friends fall away over time, allowing them to build up endlessly, producing the social equivalent of liver failure. On Facebook, there is one kind of relationship: friendship, and you have it with everybody. You’re friends with your spouse, and you’re friends with your plumber.
(Not that this hasn’t been said before…)