I judge the system by how it functions, not by contributions. And glibc/GNU userland are still the building blocks of the majority of Linux-based UNIX-like operating systems. Windows would still be Windows if the only things that were left are the kernel and the libraries. In fact, that's how operating systems evolve.

"GNU/Linux" may not seem accurate to you. But honestly, "Linux" is even worse, such a vague term that refers only to the kernel, not a very good way to name an OS family. What Linux? Android? Desktop Linux? There's no such thing as "desktop Linux." There is no clear destinction between desktop, laptop, smartphone and server, GNU/Linux can be used… whenever you want it to be used.

I actually say "GNU/Linux" because it's popular and snappy. For the same reason that the Linux crowd says "Linux." The thing is, that's the best we have, even though it has it's own share of problems, like people pronouncing it as "GNU Linux." You want to call the system liGNUx? POSIX/Linux? glibc/Linux? Pick your poison.