And why should you trust that if you they don't trust you by the mere fact of using DRM? To be open, the code has to be open. I'm yet to find such DRM. I doubt it even can exist.
Steam is just a digital distributor of games. Steam doesn't force developers to use DRM on their game. Steamworks and its components are entirely optional. If a developer chooses to publish their game on Steam, they can use features of Steamworks WITHOUT implementing the DRM part, as D:OS does.
