Hate to be "that guy" again, but in my experience, there have been as many failed and abandoned OS project as closed ones. If not more.

"Closed" is in it generally for the money, which implies at least some level of commitment. "Open" is in it for the fun and thrills and leaves the moment something more fun and thrilling comes along. Yes, in theory someone else would pick it up and carry the baton but in reality that does not happen that often. And when it does, it ends up with a multitude of forks and confused and frustrated users who eventually end up turning to proprietary solutions.

Unless, of course, your "single point of failure" also includes misuse. Then I am with you 100%.