Comment by eqvinox

I mean, yeah, sure, I can see that for open source.

And GPL'd code is not open source, it's free software. The license implies the code cannot find its way into non-GPL codebases, and you can't profit*1 from the code. (But you can profit from services on top, e.g. support services, or paid feature development.)

Now the question is, is that intersection set all GPL developers?

*1 note profit would imply distribution