i dont even understand why you guys are having trouble understanding the point of this. Valve is essentially treating your (shared) steam library as a console.
- all your games only work on your machine
- when you are playing, no one is supposed to be playing anything else on the same machine
- when you are not playing, whoever you share your machine to can now play whatever he/she wants with it
- I'm guessing you cannot play coop with friends in 2 different consoles but 1 game copy (not a console gamer so I might be wrong)
So there it is. With this sharing feature, you are lending your entire steambox with games to your family/friends. They also get an extra bit from the feature in the personal achievement department.
And no matter which way you are trying to approach this, it is still something GAINED by the community, to let friends play your games whenever you aren't playing (I believe quite a lot of people don't game through their entire 2~10 hrs being awake at home, not to mention when they go out). It's unfortunate if you won't be able to utilizing this feature to your benefit, but that's due to your personal situation and doesn't mean that others don't find it useful