Loaning implies that you're going to get the game back.
Think of it this way-- I loan my buddy Gears because he wants to try it out. Since he is now in possession of it for some amount of time I cannot play it. I'll have to wait until he's done with it. That is what loaning is.
If I were to magically duplicate my copy of Gears and give one to him then that would be against the rules because then we both are using the same game.
There is also nothing wrong with giving a person a game, but you actually have to give it to them. You can't install it and then give it to someone so that you both are in possession of it.
You can ask why but that's just the way things work. You can also say it isn't fair that you would have to use all three installs in order to let a buddy try a game but that's life. Blame the jerks that made piracy so bad in the first place.
