Excellent destruction of the straw man, but I never once claimed P-51s or any of the others were flying in 1939-41. And by 1941 the Bf 110 was already doing rather poorly as I have shown from combat data from that year. As we all know for medium ranged fighters the Allies were basically stuck with P-40s and Wildcat / Martlets until the Spit VIII arrived, unless you want to count the Fulmar but it wasn't really quite up to par.
But since you bring it up, I'll expand on the point I was making. Early fighters were mostly interceptors (short range, light, usually good to great climb rate). The "heavy fighter" was supposed to have longer range though the Bf 110 never really did as far as I know. But when they did arrive on the battlefields, the P-51 at ~ 1,600 mile range, the P-38 at ~1,300 miles, the p-47 and Corsair at ~1,000 miles, and the Hellcat at ~940 miles were all well beyond the typical range of any interceptor. They were all heavy and none were superb climbers, but they were all fast, heavily armed and had long range by WW2 standards. I am aware that actual combat ranges weren't nearly so long but just to compare like with like, the Bf 109 at ~350 miles range isn't going to be a really viable escort, and the Fw 190 was about the same.
The Germans struggled to find an aircraft for this escort role. The Bf 110 never really had great range, it was improved and yes they put huge drop tanks on them, but it never got to the point of the fighters mentioned above. The Me 210 had much better range potentially but it took too long to shake out the bugs and get a new wing, even if the Hungarians liked it right out of the gate. For more general purpose 'heavy fighters' in the sense of bomber destroyers the Bf 110 and various German night / heavy fighter types did well as long as they had interceptors to escort them, but you are back to the problem of the short endurance of the interceptors. The Germans also did alright in the long range coastal patrol role mainly with Ju 88s (1100 mile range), the Condor and some of their float planes.
The Italians mostly had the same problem the Germans did, if not quite as bad (the Re 2000 series had decent range as did the excellent Fiat G.55. Maybe the Germans should have made more of an effort to get those into production, but they were probably too late).
The Russians had mostly interceptor types though they eventually made a long range Yak 9 variant, albeit not perfect.
The Japanese of course went another way and their fighters had good (Ki-43) to superb (A6M) range, except for the Ki-61. But they weren't sufficiently well protected for sustained attrition warfare. I still think an A6M would be a more dangerous escort fighter for the Battle of Britain than a Bf 109E.
Anyway I just think it's an interesting way to think about it.