Firstly, closed source would likely be the antithetical counterpoint to GPL. I refuse to even call it copyleft, because that term is a purity test. I’m a leftist and I BSD/MIT my work so that others may benefit from it. If it’s valuable, they may contribute back. If they don’t, I still haven’t restricted their freedom or choice. An ideological position is usually one that is rigid and uncompromising. GPL/‘copyleft’ is a way of poisoning the commons.