I agree and have firsthand experience with everything you said except the last paragraph. (And Debian is a quick counterexample.)
There are viable large volunteer projects. The way they become viable is to interpret single points of failure as damage, and to fix that damage.
That damage definitely includes relying on a single maintainer's ability and knowledge to keep the project going. There's even a term for it-- "bus factor"-- which answers the question of how many of the core developers could get hit by a bus with the project remaining healthy and maintained. If the "bus factor" is 1 and the userbase is large, that's a critical bug in maintainership.
There are viable large volunteer projects. The way they become viable is to interpret single points of failure as damage, and to fix that damage.
That damage definitely includes relying on a single maintainer's ability and knowledge to keep the project going. There's even a term for it-- "bus factor"-- which answers the question of how many of the core developers could get hit by a bus with the project remaining healthy and maintained. If the "bus factor" is 1 and the userbase is large, that's a critical bug in maintainership.