There's a school of thought in change management that suggests that a time comes when current stories aren't working for the culture you're trying to move an organisation towards. A few here have said morale was low at FB right then.

At times like that, restating some important old stories and legends, salted with some useful new ones can help to galvanize people and create the culture change you want.

A good example is someone mentioned in this thread is Zuck's beat up old car. That's a great old story for the early days, but probably needed burying at the Red Book time. Clearly he's not going to drive that forever, so you need some more up to date motivational culture lore which embraces more excess while retaining how the Devs are still world-changing hackers who should work all nighters because 'we're all in this together for mankind, team'.