I think it is fair. When you buy games through GOG, you get the offline installer. Nobody can take that away from you.
When you buy games through Steam, you can only install them via the Steam client. If the Steam servers are offline, you cannot install your games. In theory, some games are without any DRM, and you can just zip them up, but even then that doesn't always work, and you shouldn't have to. That's not to take away from Steam, of course, it is great at what it does.
Providing an offline installer that works no matter what is as good as "owning" the game IMO, even if "technically" you are just purchasing a license to use the game.
That's what private trackers (and torrents in general) are for, but private trackers commonly share copyrighted materials, which is of course not so legal depending on where you live.
Honestly, as cool as this is, I just keep collections of downloaded entire game libraries like PS1, PS2, PSP, 3DS, NDS, GB, GBC, GBA, NES, SNES, etc.
I'm more interested in preserving my save games, which I can dump myself on my modded 3DS for 3DS and NDS games, plus my PSP I can just copy paste those save games from the memory card. Those are more what is really irreplacable. Everyone has my games, not everyone has my save games.
$100 LOL