GM is definitely more general purpose, fantastic as it may be. It feels like it is mainly included as a sub-package within larger private pipelining apps (where it is faster than its ImageMagick parent, and thus, a nice replacement.) or for image conversion sub-pipelines on photo sharing sites.

To Robs point, it was not necessarily developed specifcally for VFX and not necessarily a foundational VFX package component like OCIO or USD, but super close potentially. Maybe an honorable mention section is due for apps like this and DJV?