Why don't Gnome or KDE produce their own distribution (or other desktop projects for that matter)?

Question

When I think of the recent debacle where Canonical and Gnome disagreed and each went their own way in terms of producing a new desktop, I wonder: Why doesn't a desktop project like Gnome produce its own distro, rather than wait for other distros to punt or ship its product (if you can call it that)?

Answer 1

On top of mattdm's answer, I'd like to add:

• Their missions are to create (good) desktops, not distributions. You might as well ask, why don't FLOSS project X that isn't a distributor (Apache, Python, Linux kernel, ...) produce it's own distribution. Their mission is to produce a (good) whatever, not a distribution.

• The people working on these desktops are often working for distributions as well. For example, many of the most important people in GNOME are employed by Red Hat. Fedora (community distro supported by Red Hat), which is so bleeding edge that it sometimes receives updates before module tarballs are available, is a first-class GNOME distro as a result.

Answer 2

I think "Because it's a huge amount of work."