You could use the same reasoning to argue that nobody in the free software community would sit on the C++ committee, or that nobody in the free software community would get involved with POSIX. But the former has substantial free software representation and the latter is by now pretty much entirely driven by the needs of the Linux community.
So your reasoning appears somewhat flawed. (Or, rather, contains an erroneous implication: that it requires quasi-gurus, sure. That there is something preventing these quasi-gurus from ever participating unless they are backed by a non-'volunteer organization', possibly. Your implication that non-volunteer organizations are necessarily proprietary software companies is plainly false. If this implication is dropped, your last paragraph becomes a non sequitur.)