A closed system is closed because all of the edges aren't open.
I think you are misquoting the laws of thermodynamics.
https://en.m.wikipedia.org/wiki/Laws_of_thermodynamics
It's very important to understand the rule and the implications. It's self-consistent. They are axiomatic, so if you can come up with a better system that and demonstrate it you can beat it. But until then they're laws.