Nonsense. When a company/individual takes open source and enhances it while keeping those enhancements proprietary it requires the exact same 'duplication of effort' to reimplement those enhancements as open source or even in another proprietary setting. GPL prevents proprietary use but at the same time it prevents a great deal of the very 'duplication of effort' which you just described by requiring that derivatives (enhancements, modifications) be available as source code.
Originally Posted by silix
This is the type of cognitive dissonance I only seem to find in the reasoning of BSD advocates, proprietary is just fine and dandy while GPL is somehow bad?
It makes no sense. Now I don't agree with the notion that everything has to be open source, but I can understand it logically from a 'philosophical' standpoint, I don't agree that everything should be proprietary, but I can understand it logically from a 'corporate' standpoint.
But saying that from an open source perspective, proprietary is fine but GPL is somehow bad? You'd really have to be either a proprietary troll or a pure-bread BSD zealot to reach such a conclusion.
If you accept the notion that programmers want money in exchange for their code, how could you possibly not accept the notion that programmers want to have changes made to their code available to them in exhange? This is what they get with GPL.