This is a confluence of three cultural impedance mismatches.

The first is that some non-Debian distros focus themselves primarily on selecting exactly one, and only and forever one, DE for the distro. I don't know why this annoying fad spread into an annoying industry standard a couple years ago (OK maybe a decade ago). So Kubuntu = KDE and Ubuntu = Gnome and never the two shall switch, ever, without a wipe and reformat and reinstall of something else. Debian is culturally different and you just install what you want. Its almost like a bad Zen koan. "All states have a state religion. The US has no state religion. What is the state religion of the US?" Well its a question that culturally makes no sense. Sound of one hand clapping. Mu. So there is no official DE for Debian, and thats good and how it should be and we all like it like that. But it makes conversations awkward and weird at a cultural level.

The second cultural mismatch is there's a pretty intense focus on being able to distribute A Debian cdrom (emphasis on singular) that will boot and install a minimal system in Debian. This demand or desire or cultural trait requires that some working subset of Debian be found that will fit in 650 MB. Other distros just don't care or perhaps they only really support netinst or perhaps their "minimal single disk install" is a SL (or DL?) DVD. Gnome and KDE just are not going to fit along with the required stuff on a single 650 meg cdrom, so bye bye. I see this gradually shifting in Debian... I haven't done a "single disk install" in many years... All PXEboot netinst for many years. I think my experience is common that sometime in the 00s I switched from optical media to USB/netinst "media". But this cultural trait is how it used to be and it still has momentum. Someday momentum will build in a new direction, but it hasn't yet, maybe next release? In the Debian culture you flow with the river or at most try minimal diversion, you don't shout at the waves or lead a cavalry charge into the ocean.

The third cultural mismatch is corporate or semi-corporate distros make UI and all other decisions based on marketing, PR, mostly a bunch of tail chasing imagination of what a theoretical user might like, or what we will tell them to like. Extremely top down organization where the packagers are told exactly what to do. However the Debian people make Debian "for their users" and the most important users with the biggest voice are the Debian devs themselves... Its a intensely bottom up organization. Out in the real world, no one seriously WANTS to use KDE or Gnome, they just feel in an "emperor has no clothes" way that yes they personally don't like either, but that mythical "everyone else" just loves gnome and/or kde so they'll go along to get along and select one. No one in Debian would (intentionally) stand in the way of the work of other maintainers, so if someone wants to package KDE or Gnome, the mythical "everyman developer" wouldn't stop them, but if no one wants to use KDE or Gnome, the mythical "everyman developer" is not going to force everyone else to use one, just like they wouldn't force a maintainer or user to do things in general. Another way to look at it, is its very social darwinist, we'll package up some software and if people want it, it grows, if not, it disappears. Not an intelligent design approach were the C*O and VPs decide which software will live and die. Its very hard to map top-down cultural thinking about what DE they'll force the users to use, into a bottom-up culture like Debian. So its weird / uncomfortable / difficult to even discuss the concept of what we'll force the users to use. It doesn't culturally make sense to use top-down talk to discuss the behavior of a bottom-up org.

The TLDR version, is that culturally this whole argument doesn't make any sense in Debian.