Others have said it already, but it bears repeating since it's a common misconception:Very few games work like this, because there is pressure from Steam fans for games to include Steamworks features like trading cards, leaderboards, etc. All of these require the DRM.
Steam is DRM, but a tiny number of games aren't fully implemented on the platform so lack steam features, the first of which is always DRM
This is 100%, entirely, completely wrong.
Unlike most other platforms, Steam DRM is not only completely optional, it's actually opt-in rather than opt-out. As in, you have to actively work on integrating DRM if you want it. You can also integrate all other features without DRM (though of course people need to be connected to the network to use features with an online component such as cloud saves).