Analogy time: I feel like everyone thinks of Facebook and Twitter as Coke vs Pepsi, including Twitter's head honchos. Facebook have this unique combination that is massively successful, Twitter are desperately trying to imitate it.
They should look at it more like Coke and Sprite. Sprite offers a different taste, it's for us guys that like lemonade. Why not crush the lemonade game, rather than gun for Coke? (I know that Sprite is owned by Coca-Cola, the analogy doesn't run forever)