Over 1000 Googlers were cranking on Google Plus, which at the time was a Facebook copy cat.
What makes Facebook so threatening to Snapchat is the aggressive cloning in tandem with it's pre-existing, larger network.
By the time Google decided to clone Facebook, the Facebook Graph was already more powerful than the GMail graph (which is what Google Plus was built on).
Facebook copycat? It was poor take on Facebook. Bad design, bad decisions, bad UI and bad UX. There was no vision for it, Google Plus would be much better as LinkedIn killer than Facebook killer.