We aren't comparing performance, we are comparing design philosophies. Lets say for an argument the RAF gave Supermarine a design brief saying they want the Spitfire to have range and maneuverability as the primary considerations like the A6M was, Supermarine would have made what is accentually an armed PR model but that's not what the RAF wanted. The A6M was designed for a very different war than what the Spit Hurri 109 and later the 190 P51 Tempest P47 foughtA pretty narrow viewpoint. You ALWAYS want to compare the enemy's aircraft to yours, if only to verify your view of it's potential. Many times, it give designers something new to shoot for in the next airplane, AND allows you to tell your pilots how to handle encounters with it.