Google+ is shutting down after several years of a failed effort to rival Facebook. However, it is not officially closing down due to failed competition. It is ending services because a vulnerability exposed half a million users’ data. Specifically, the issue lies in the Google+ People API, which had a flaw that exposed usernames, email addresses, gender, DOB, etc. to third party developers. These things are not infrequent. However, one has to wonder if this happened to Facebook, the result wouldn’t be so disastrous. This was likely just the nail in the coffin for Google+. Only 438 developers could have had access to this vulnerability and there apparently is no evidence that any one of them were even aware of this.
https://thehackernews.com/2018/10/google-plus-shutdown.html