(Now I realize a big problem with Sublevel, same problem as with Facebook, "liking" something that is bad feels... wrong.) Open Source has not yet figured out how to close the loop on auditing software for performance and quality. Those aren't "fun things" to work on, and they're usually done in anger: MariaDB, Joomla, X.Org, Carrier. The most famous recently is of course LibreSSL. Its good for software evolution as long as the new maintainers have a solid vision and time for the commitment and increase the bus factor.