Well, if you apply this standard, maybe the only strategic aircraft in the whole war was the B-29. Let's take the war in Europe. If you threw enough P-38s at the problem, you could have replaced the P-47 and the P-51. The P-38 wouldn't have done the escort or ground attack job as efficiently, but eventually it would have gotten done. Heck, you could even take an F4U, put 100-120 gallons of extra gas in the wings, take off the tail hook revise the supercharger gearing, and if necessary, remove two machine guns, and it could have escorted bombers into Germany.
If you're going to engage in reductio ad absurdam, take it all the way: no aircraft were strategically significant because wars are not won by aircraft. They are won only when a filthy grunt kicks in the door of the palace.
It's all nonsense anyway: the real candidates for the most strategically important aircraft of WW2 are the Yak UT2, the J-3 Cub, the Tiger Moth and the like.