So general roadmap was usually build up a network of very niche TGP sites (later, Tube sites) and only push around to your own network (so no external crap or popups) until you get a soid audience of bookmarkers (daily returners) and once you're confident you can start producing 10,000+ outclicks a day, THEN add your own paid stuff on top.
Trying to push payments really early just makes people hit the close tab... adult is all about getting bookmarkers
Basically, the "retention" in the Pirate Metrics funnel. Facebook didn't want to put on ads until they'd build years of loyalty and bookmarkers. Once you're totally bought into the service, (one hopes) that you wont mind the new paid ads that start appearing.