How is GOG functionally different from Steam? They're still just a middle man. For actual DRM-free software, both GOG and Steam are nothing more than a convenience layer. If they're anything more than that, the software simply isn't DRM-free.
As far as I know all the games you can buy on GOG will be completely DRM free.
Requiring a network-connected proprietary client to install the software is itself a form of DRM.
> For software with other forms of DRM built-in anyway, who cares if the installer has it?
Again, GOG does not distribute games that include DRM, whether in the installer or in the game itself.