I've never understood this designation. What does it "really" mean other than FSF could never get their act together and make an OS so they ride on the "coat-tails" of Linux. My windows box has more GNU software installed than any of my linux boxes..should I start calling it: GNU/Win7?
I'm not sure it's true and you seem not to know GNU Hurd (another kernel for the GNU system). Linux designates only the kernel, not the whole operating system. GNU/Linux is an implementation of the GNU system. The FSF wrote:
Fortunately, we didn't have to wait for the Hurd, because of Linux. Once Torvalds wrote Linux, it fit into the last major gap in the GNU system. People could then combine Linux with the GNU system to make a complete free system: a Linux-based version of the GNU system; the GNU/Linux system, for short.
I think FSF's reasoning for really pushing the term 'GNU/Linux' is that Linux distro's rely heavily on GNU software to run. In practical terms, you cannot have a Linux distro that did not contain GNU software, however you could have a Windows system which didn't contain any. I think it's partly also that they feel unappreciated since a lot of effort has been put into building GNU software, which in turn has helped to push Linux, such as GCC.
I think it's a bit of a contradictory argument. The whole point of having 'free as in freedom' is so we don't have to adhere to silly rules like referring to 'Linux' as 'GNU/Linux'.
It is not contradictory, it is just a different conception of the software freedom with which I agree.