I understand distributions (Debian, Arch, etc.) are what users will use. But those distributions have a foundation to build off of (that's what I'm referring to when I say OS), and that foundation most distributions use is GNU and Linux.
GNU came first, and the final piece of the missing puzzle was Linux. Adding in Linux shouldn't overshadow all the incredible work the GNU project took over 7 years to create.
Android is a different issue, although it certainly puts a hole in the logic of calling the desktop OS Linux. "[Android] contains Linux, but it isn't Linux."