Hi Dennis, thanks for commenting.
I think just about everything Google does on the Web today is intended to boost advertising revenues. I also think it is fair to say that is pretty much what Facebook and all the other social networks have in mind and why we have free access to these wildly popular sites.
It is a bit of a trade off. We get to use these sites to connect and do all the things we do there for free and the owners of the sites have the benefit of millions of people's eyes.