I just though about this thing that the whole library is locked, when anybody plays a single game from it. So what happens if I create a new account for each game that I buy? Then I would have a separate library for each game. So when I want to share a game I can still play the other ones. I only have to log into the other games account. Is this a thing, can this work?

One could also use fewer accounts lets say 2-3 so that only part of the games are locked any time I want to play. Are there any restrictions that would prevent me from doing this?

I assume that'd still work. My theory would be you and a few others could make an account where you would all chip in to buy games (mostly single player games that can be finished, don't want someone hogging that account playing DotA 2 all day), and agree with set times for each of them to play.