what is the point of this?
It's two weeks late though, would have been a great "April Fools but we're serious" thing.
It's currently used mostly as a "painting's signature", a point of pride for the team behind the site. Looking through all the comments in this thread you will see many other examples.
1. You'll come across it and apply for a job at Google.
2. You'll have a positive interaction with the Google brand.
A big part of this: it's something people want to share. Without that element, it would only ever be seen by a few dozen people.
So for me this is a negative reflection of the Google brand.