I see your point but the Hellcat provided support to dive bombers such as the hell divers and sbd, which is the main reason the us had dominated the Japanese from 43-45. The Mustang would occasionally see conflict with German bf 109s but if you look closely most fights were pretty close while on the other hand for the hellcat, the hellcat dominated the skies, as it was faster, it wasn't limited to airbases as it could be launched on an aircraft carrier. Also its 6 50 caliber machine guns would tear apart the zero within seconds.