Big mistake :
Steam *IS* DRM !
So you cannot say "Steam is DRM-free" - because Steam IS the DRM !
Since Steam = DRM, one just cannot say "DRM-free on Steam". It's like saying 1 + 1 = 3
Try to keep up, this has been explained before, even in the link I posted that you replied to. Steam is not DRM, it's a digital distributor. Steamworks is a service available to publishers on Steam, which has an optional DRM component. Look at that list of DRM free games on Steam again. I can copy any of those games to another computer that doesn't have Steam on it or an internet connection and they will run. Does that still mean they have DRM because they came from Steam?