Some political systems exist, others used to exist, some have not yet existed. Can we declare any of them impossible, even the most absurd? All that exist failed in some way.
Before the Wright brothers went to Kitty Hawk, many people argued that heavier than air human flight was not possible. I suspect this was a waste of breath. How can we know when we waste our breath, before we witness the idea we oppose in flight?
Purely political ideas are nebulous, vague, abstract, theoretical. How can we test them fairly?