Imperfect is perfect. Why? Because your assumptions about what people want are never exactly right. Most entrepreneurs create great products through a tight feedback loop with real customers using a real product. So don't fear imperfections; they won't make or break your company.
— Reid Hoffman
One (of the many) interesting things Zuckerberg discussed was how Facebook moved from a "move fast and break things" ethos to "move fast and break things, with the right infrastructure".
Aside from an obvious acknowledgment of the company's reality at the time, it also indicates a willingness to not only adjust strategy, but to change the principles by which the company operates. This speaks loudly about Mark's mettle.