Fixating only on features you don't care about to argue your point while omitting the features of Steam you find useful due to it not strengthening your position is rather misleading. Steam workshop is another I forgot I have found useful for mods for certain games.
GOG strengths like DRM free and install files are good enough to stand on its own without trying to make it as though Steam's feature only have things you see as worthless.
I use Steam Input to set up mouse input on my controller to utilize gyro aiming, which lets me play against mouse players without utilizing aim assist.
And I also set up keyboard inputs on my controller to be able to utilize keyboard short cuts over relying on things like the weapon/item wheel.
Makes it so I get a controller experience that is more mouse and keyboard like that I couldn't get relying on default controller schemes.