kde-settings includes xdg-user-dirs support/usage, but (as of kde-settings-3.5-26), didn't include Requires: xdg-user-dirs So, there's potential for (kde) users to not have xdg-user-dirs in place.
Good news is that xdg-user-dirs is the default package-list for comps' groups kde-desktop and gnome-desktop so this would theoretically not affect everyone anyway.
Point is, if xdg-user-dirs isn't installed, kde will use ~ instead of ~/Desktop for one's "Desktop" location.
* Fri May 18 2007 Rex Dieter <rdieter[AT]fedoraproject.org> 3.5-27 ... - Requires: xdg-user-dirs (#240556)