"As the lender, you may always access and play your games at any time. If you decide to start playing when a friend is already playing one of your games, he/she will be given a few minutes to either purchase the game or quit playing."
So I can authorise a person to use my account. I can then, at any time, play my own games. But if that other person is playing a game it will kick them off.
I am really excited about this feature. Around the time Portal 2 came out my partner and I lamented the fact that we had to buy two copies if we each wanted to play on our own account, considering how account sharing is against the TOS.
I'm sure the people who do account share to get around this will be very happy to know that they don't have to go over and log in their significant other whenever they wish to play a game the other owns.
I don't think it is a reasonable restriction at all. Besides the most devoted fans, I don't believe many families would purchase multiple licenses to a lot of games just to be able to play them simultaneously. These kinds of terms don't really increase revenue but they unnecessarily damage the experience at the same time. This is exactly the sort of stuff that makes pirating more convenient. As I've mentioned in another comment, the Mac and iOS App Stores don't really have these limitations.
Valve are not giving away a single copy of anything, they are licensing intellectual property with specific terms. I'm advocating licensing terms that allow licensees to simultaneously install and use licensed items on all computers owned by them. The terms of the Mac App Store already allow this.
I'm kind of surprised that game companies now expect you to pay for a game twice to play through a two-player co-op campaign. Remember when local multiplayer was a thing? When you'd buy a game, and several people would sit around a TV getting "simultaneous value out of it" for the cost of that one purchase, because that was the game's value proposition to begin with?
So I can authorise a person to use my account. I can then, at any time, play my own games. But if that other person is playing a game it will kick them off.
I am really excited about this feature. Around the time Portal 2 came out my partner and I lamented the fact that we had to buy two copies if we each wanted to play on our own account, considering how account sharing is against the TOS. I'm sure the people who do account share to get around this will be very happy to know that they don't have to go over and log in their significant other whenever they wish to play a game the other owns.