I can believe there are some open source advocates who claim your first bullet, and there are a few cherry examples (i.e. Linux), but I'm guessing a lot of us a

I can believe there are some open source advocates who claim your first bullet, and there are a few cherry examples (i.e. Linux), but I'm guessing a lot of us are better represented by, "I appreciate when other developers share their work with me, so I'll share my work with other developers." From this point of view, it's easy to see how the GPL is an impediment to professional (proprietary) developers, and why we'd choose a license better suited to sharing with ourselves.