Found Licenses nail seeks hammer, any hammer
I make my code available for use in free software, and not for use in proprietary software, in order to encourage other people who write software to make it free as well. I figure that since proprietary software developers use copyright to stop us from sharing, we cooperators can use copyright to give other cooperators an advantage of their own: they can use our code.
Not everyone who uses the GNU GPL has this goal. Many years ago, a friend of mine was asked to rerelease a copylefted program under noncopyleft terms, and he responded more or less like this:
Sometimes I work on free software, and sometimes I work on proprietary software—but when I work on proprietary software, I expect to get paid.
He was willing to share his work with a community that shares software, but saw no reason to give a handout to a business making products that would be off-limits to our community. His goal was different from mine, but he decided that the GNU GPL was useful for his goal too.
My argument for liking [GPL] version two, and I still think version two is a great license, was that I give you source code, you give me your changes back, we’re even.
You don’t have to use Linux. If you do use Linux, the only thing I ask for is source code back. And then there’s all the other verbiage in the GPL version 2.0 about exact details, and those aren’t important. And that was always my standpoint.