The human psyche, whether P or J or whatever, desires to find "tidy" intellectual unity in a single system. The existence of different varying systems frustrates this desire for neatly packaged answers, just as it may frustrate physicists to have two different explanations of the cosmos, one by general relativity and the other by quantum mechanics.
I would prefer to find a single Truth, but lacking any, I am satisfied to just have fun and go with what I've got to work with.
But if you have knowledge of various systems, don't you sense any identity at all between them? If so, why not seek out a single unified system of thought to explain the various identities?