I feel like it would have though if Glimpse had managed to become the default image editor on at least one major distro, just by virtue of people stumbling in to contributing some fix or addition to ‘the thing that came with my OS’ without necessarily being aware of the history.

Like the FFmpeg/libav fork that eventually got back together. Or Compiz/Beryl, or Emacs/XEmacs, or GCC/EGCS, or whatever :)