Dresden accomplished nothing.
Most of the bombing accomplished nothing.
Defeat was accomplished by Willie, Joe, Tommy, and Ivan
in their muddy boots.
It prevented the reinforcement of the Eastern front by at least 35 divisions of German assets, allowing the Soviets to overrun the German East, and forcing the Germans to redeploy those forces less efficiently, weakening their Western front - this shortened the war considerably.
Because of Dresden, far more Willies, Joes, Tommys and Ivans were still alive at the end of the war than would have otherwise been the case.