Your kind of skepticism is ultimately one of the few things that holds corporations in check, so I am not discouraging you from persistently aiming it at Google

Your kind of skepticism is ultimately one of the few things that holds corporations in check, so I am not discouraging you from persistently aiming it at Google, Facebook, et al. But that being said, I was a full-time dev there for 5 years, and I can say with a (however misguided) degree of certainty: all of those projects have one goal in mind - to make the experience of using the web better. Whatever else is true about the dangers of monoculture, Google's intentions are benign.