How is this not also true for Steam? Unless the game itself has DRM, I can copy game files to an offline machine that doesn't have Steam installed and launch and play them normally.
Edit: Glazing GOG for this while insisting "sTeAm iS dIfFeReNt" is like buying the cereal box that says "Asbestos Free!" on it.
Ever since that Sony tweet, all these kids are, overnight, developing all these strong opinions about shit they never cared about before, based on nothing but hype, memes, and regurgitated streamer slop.
Physical media has licenses too. GOG purchases come with licenses too. Optical media rots. And Steam isn't secretly Sony (yet. They probably will be after Gabe dies).
Downvote me all you want, it doesn't change the truth and reveals much more about you than me.