I would tend to disagree with this. Facebook's customer is advertisers, which inherently requires scale/ad placements + live auction system + the FB graph match

I would tend to disagree with this. Facebook's customer is advertisers, which inherently requires scale/ad placements + live auction system + the FB graph matchmaking. I am not familiar with the internals of Uber, but they earn revenue if they can get a rider in a car, pay both parties, and then take a cut.