Private here just means not out in the open, not absolutely private. This doesn't seem like a very "strange" way to use the word to me. I think the OP does a g

Private here just means not out in the open, not absolutely private. This doesn't seem like a very "strange" way to use the word to me. I think the OP does a good job of outlining why this is preferable to Craigslist for your run of the mill buying and selling, namely that buying from a known entity is generally preferable than buying from an unknown one. Facebook makes a set of tradeoffs regarding privacy and monetization, and they seem to be very popular. You assign a lot of agency to Facebook for orchestrating all of this, when really they are just providing to what the market wants: a free (as in beer) social network. /counter-rant