It’s intentional, it’s a way to brag. They don’t need to at all. There’s a reason why nobody at other companies does that - people at other companies are normal and don’t think they’re gods gift to the world.
It's required by company policy. Otherwise the comments could be seen as astroturfing. The policy is so strict that it specifically says you need to put a disclosure in every individual tweet, a disclosure in your Twitter bio isn't sufficient. I think that part of the rule is broken frequently though.
Interesting. Is it limited to Twitter? I can see the company fearing a backlash in social medias where you're operating under your own name (and thus can be traced back to Google) but what about anonymous and semi-anonymous forums like HN?
I re-read it, and it actually doesn't explicitly mention Twitter. It does mention how you can disclose using hashtags, which is why I misremembered it as talking about Twitter, because Twitter and hashtags are so linked in my mind.
It looks like it applies to basically any online post/comment, regardless of if it's anonymous.