Some people do call it GNU/Linux officially, such as the Debian Project, but casually yeah it's not really used so much because its weird and awkward to say. 99% of the world just calls it Linux and that's fine.
Honestly, if RMS were less of a jerk about it, I'd feel the other way: he and his organization did a lot, and it'd be great of Debian to credit them. But his juvenile bizarre obsession with it, at least for me, is a perfect example of the backfire effect.
RMS, the FSF and the GPL have had a phenomenal impact on software. But apart from RMS's own shortcomings, the result of that phenomenal impact is that his role is diminshed, to a de minimus level.
It's like Tim Berners-Lee: massive impact on the world but by now no real role. Nothing wrong with that (especially when it's such a nice person as TB-L).