I think it's more that they actively courted assertive people with opinions and then created a culture where you can bring your whole self to work. They did this so that they could get the benefits of creativity, which inherently requires emotional engagement, which requires that you not repress your emotions. (It turns out that it's not possible to
selectively repress emotions: "I've got to watch what I say about politics" subconsciously spills over into "I've got to watch what I say" which spills over into "I've got to watch what I say about anything new and controversial", and you lose the latter well before the former.)
The part that's biting them is that now that they're 100,000 people, creativity is wasted anyway, because any brilliant new product idea will get killed long before launch and if it doesn't it'll probably catastrophically damage Google's brand. So the upside of this cultural decision is worthless to them, and the downside is incredibly chaotic and difficult to manage.
I think we'll see a shift away from this at Google, but I think other startups will still consciously embrace it. When you're 10 people and are about to go out of business if you don't come up with a brilliant idea, your incentives are dramatically different from when you're 100,000 and make tens of billions from your existing business lines every quarter.