There is no joining any company or anything remotely like that no matter how hard you try to squint. The single rule in GPL is no more than any other usage-of-commons rule like don't pee in the pool or litter in the park.
The park is still free for anyone to use, you just can't fence off a part for yourself and start operating your tire-burning business in it. The body of people who either first donated it or the tax payers who voted for it set some terms for usage, and now you can either enjoy the goods under those terms or not.
But what's interesting is how some people have this kind of reaction and try to come up with this kind of argument over the act of being generous.
Are you sure GPL isn't even worse than you said? Why be so nice? Are you sure it doesn't also eat babies?