Google+ did not fail for technical reasons. Everything I saw about it was technically better. It failed for social reasons, facebook already exists and has everyone on it.
It didn't failed for Social Reason, it failed because it was an inferior product for the mass. Facebook succeeded because its concept is simple enough for even your GrandMa and Dad to understand.
All of those did something different to facebook. None of them attempt to replace it. Googles problem is not that they can't move fast, they already move too fast. Every year they totally rebuild an IM platform and create a new music streaming service.
Google+ was designed by geeks for geeks.