Now now, let's not fight. The P40 was obsolete for the entire war, save for the very beginning. It was an obsolete plane killing lots and lots of other obsolete planes. That's the only reason it has such a high kill rating. Killing 50,000 Ki27s is like killing 400 zeros. Makes a big difference.
Killing 100,000 (all numbers hypothetical) obsolete 1930's IJA bombers got them out of the fight, but doesn't mean that it takes much to kill a bomber from the '30s. Hell a spitball from a hang glider can get kills but that doesn't mean that this is by ANY means a good fighting platform.
The P40 was continuously updated throughout the war in the vain hopes of improving it. Instead, it was behind the performance curve of most planes in most nations out there. It didn't serve in the ETO because it would have been dogmeat. Instead it was delegated to the theaters with less intense fighting.