They might have online features that obviously you need an account for and a online connection but thats not DRM.
Debatable, but beyond the scope of this discussion.
GOG games are always DRM free.
Multiple users have, in the past, reported being unable to successfully launch Victor Vran (as sold and distributed via GOG) if the game was denied access by a firewall. We can equivocate all day over whether that program behavior was intentional or unintentionally caused by the incorrect removal of potential DRM features, and whether that program behavior does or does not constitute "DRM", but the point is that it was a game on GOG that (potentially) would not launch if denied firewall access, and that sort of thing is relevant to my decision of "should I purchase [game]?"
Instead of parrotting "GOG games never have DRM" you need to accept the reality that mistakes happen, grey areas exist, and proper investigation is the only means of dispelling doubt.