I don't share your black/white view of the software world, and I respect developers' choice of license (whether its proprietary, copyleft or permissive). To claim that those who reject copyleft licenses somehow discourage code reuse excludes those who support permissive licenses and reject copyleft licenses. It's obvious that permissive licenses encourage more code reuse by a wider developer audience since this audience includes proprietary developers and developers who simply don't wish for copyleft licenses to extend those copyleft terms to their own work (which is understandable). A copyleft license only really encourages code reuse within the FOSS community. That's the duh part.
I don't know why you assume that a copyleft license somehow encourages proprietary developers to make contributions. It's still the sole discretion of the companies and developers to contribute to a copyleft project. Further, I don't understand why you assume that a permissive license does not encourage these types of contributions either; this very thread and phoronix article serve as a contradiction to your statement (since launchd was written by Apple).
Software licenses are software developer issues. Why so many software users care so much baffles me. The license does not change the user experience at all.