It means what people actually develop, support and use in the real world. KDE has no real support. Suse, Red Hat/IBM and Canonical all develop and support Gnome which is largely what has made it so polished.
Also, I'd wager Gnome is absolutely used by 90% or more of Linux users.
> Also, I thought opensuse (or whatever new name they’re using) was KDE default but with a choice (like Debian)? At least that’s what DE I got last time distro hopped to it.
Depends "which" openSuse. OpenSuse Leap is going away since Suse (the corporation) is doing away with non-immutable distros. Whether it keeps KDE remains to be seen as MicroOS has lots of issues with KDE. Tumbleweed has KDE as the first choice still, but it's basically hobbyist-only from this point since there's no equivalent Suse distro. Aeon is Gnome-only.