It's fiction, and the freaking author only knows basic duality, Yin-Yang and tries to extrapolate that into his story and made those 4 duality as fundamental duality.
Existence governs all of existence, basically, It's the concept of concept.
Nonexistent governs all of nothing, basically the concept of non-concept.
Time governs causality, time, history, etc.
Space governs dimensions, reality, etc.
And, etc.
The 4 Duality cover all necessary concepts for the entire reality to works under each respective umbrella (Duality).