Facebook didn't have a competitor with 20x the market cap doing a great job of rapidly copying their distinguishing features.
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).
I said "great job".
> Plus, by comparison, had upwards of 1,000 [people on staff], sucked up from divisions across the company.