I use the command line a lot, but really, how big of a contribution is cat, ls, find, etc.? It's not like these are extremely complex or difficult programs; the GNU version is still the dominant one mainly because it works fine and it had momentum. I acknowledge that these have grown to be relatively advanced and it may not be an overnight job to rig up a replacement, and I appreciate the effort that has been put in to them by GNU developers, but it certainly wouldn't leave us desolate if we all had to stop using GNU code for some reason. There are non-GNU implementations of these programs already.
Other than that, how much of my normal CLI usage is attributable to GNU? I'll give screen. What about OpenSSH, Python, htop, pacman, etc.? I use these a lot and they are not from GNU. If I am primarily running Python programs on my Linux box, should I call it Python/Linux since the Python Foundation is the most significant contributor to my userspace experience?