Steam doesn't require DRM. It certainly supports Valve's DRM and third-party DRM but it doesn't require it: http://steam.wikia.com/wiki/List_of_DRM-free_games

If you consider being required to login into Steam once to download the game and run it the first time in Steam to be DRM, then yes I suppose Steam will always have DRM. That's not much in the way of DRM though.