I'm just quoting the Free Software Foundation themselves. I didn't say I agree with them. It's a deceptive use of language that is rather unbecoming of an organization normally so careful with its words.
Edit: For the record, I think the GNU Project's biggest contributions have been to the desktop, not the server world.
I'm familiar with the history of GNOME, and somewhat with Xamarin and Mono. While I have made that argument in the past, it was pointed out to me that the GNOME name was used to ride off the coattails of the popularity the GNU project had in the '90s, and they ended the association when it stopped being convenient for them.
(A GNOME developer pointed this out to me using this language; I could link you to the interaction, but it was on reddit)
This also includes the proprietary NVIDIA driver, which only works with glibc.
I think this is a strange characterization of the GNU Project's goals. This is the Initial Announcement for the GNU Project:
Do you know something I don't? I don't think the GNU Project was against multimedia software; they were just focusing on the more fundamental stuff first.
The GNU Project's biggest contributions were when the kernel was in its infancy. The most major contribution is undoubtedly the GPL. Without it, Linux would not be where it is today. I think enough has been said on that subject, but it's what made RHEL billions. It's the philosophy of free software that has made so much of the programs today possible. It's incredibly important.
Obviously, we also have the GNU Project financially backing Debian GNU/Linux in its infancy. And while you say GNU wasn't involved in the GUI layer, that's not true. They worked on the free Harmony toolkit as a matter of high priority, and would have kept working on it if GNOME had not been so successful. Thanks to the success of another GNU project, GIMP, the GTK toolkit was able to be repurposed for general usage.
I don't think it's fair to discard contributions that never panned out like HURD and Harmony, because it shows GNU was actively involved in making the desktop better for everyone, which has really been its mission from the start. Maybe they're not "the backbone" of the desktop, but I think it's fair to say their biggest/most notable contributions have been to the desktop, not the server.
I don't contribute to the GNU Project because frankly, they don't do anything I consider worthwhile at the moment. I don't contribute to the Linux Foundation, either. I contribute to user-facing software I'm interested in, like Lutris, GIMP, and Kdenlive.