There was a time where other distroes were contemplating if they should ship with KDE or Gnome desktop, while Debian would say; we will ship with both KDE and Gnome, and not only that, all other desktops too, and all window managers we can find, and additionally any other gui too.
Free software? You got it, we will champion that too! POSIX? Sure thing folks, we will support anything we can, or do our very best at doing so, and to make things more difficult, we will support it on the most...