Mrtennis: "why do people argue over whether other people hear differences between any two components?"
Why do people argue over religion, science, medicine, or any other topic? It's been that way since the beginning of man. That also covers your entire last paragraph. You don't see a needed aspect for questioning and debate, with regards to human rationale? Just ignore the topic of "audio" for a moment, and think of a "human" world, in any aspect, without debate.
It isn't just the thses audio forums!