This is true, but irrelevant. There is plenty of non-copyleft software that is thriving. FreeBSD, PostgreSQL, X, Rails, you name it. None of them have succumbed

This is true, but irrelevant. There is plenty of non-copyleft software that is thriving. FreeBSD, PostgreSQL, X, Rails, you name it. None of them have succumbed to the fates against which GPL proponents advertise their license as the only defence.