"Valve's attempt at a console-killer"? Really? No, this is Valve's panicked reaction to what had been the Xbox One's planned digital game sharing, which MS had to temporarily shelve while they re-wrote how the Xbox One handles disc-based games. If you don't remember, the Xbox One was originally going to let any console owner set 10 people to be members of their family sharing plan. Those "family" members (MS stated that they didn't have to be family), could then check out any game out of the owner's library at any time.
Here's the difference between the two plans:
Steam: If the owner of a shared game wants to play any game in their library, any person playing the shared game will be booted, even if the owner wants to play a different game than the one being shared. You are accessing a shared account, not a shared game. Also, Steam knows this immediately. The person accessing the shared library "will be given a few minutes to either purchase the game or quit playing." You can infer from this that shared gaming will not support offline mode... I.E., Always-on internet access is required to access a shared library.
Xbox One: The system treated shared games as a temporary license transfer. The library wasn't shared; individual games were. Your friend could play the game you lended to them without interrupting your play of any other game on in your library. To handle this license sharing, the Xbox One would, once per day, detect the status of the games and licenses on a console. Despite the constant FUD, the Xbox One *never* required an always-on connection. The requirement was for the console to be connected to the Internet at least once a day while the system did a license check for lended games.
So yeah, you can call this a great accomplishment by Valve and their "console-killer" if you want. You can hail the greatness Valve. But you have to ask yourself, why when Microsoft did it, were they burnt the stake and when Valve does it they're uplifted as a savior?