Can two users share a library and both play at the same time? No, a shared library may only be accessed by one user at a time.

Yeah, I took this as 'both play the same game at the same time' which seemed obvious. I didn't realize 2 different games couldn't be played. I mean, I get what you're saying about 'renting' my games to 10 people, but looking at it in terms of my PS4 analogy, it makes total sense to me that 2 people in the same house could play 2 different games from the same library - They've been paid for. And only 1 person is using them at a time, the same way they would be in a house of multiple consoles and 1 copy of a game.