> What did Livejournal, Xanalga, Myspace, Tumblr, all screw up

Don't forget Friendster!

Mainly bad-luck in being too early or too late, though MySpace had some self-inflicted problems with performance and overcomplicating the interface (by allowing customization).

This just feels like special pleasing. Why did Facebook get the timing exactly right and what was different about that time vs. a better understanding of user wants, well planned rollout and promotion strategy that created desire to have it, and not being too greedy.