Dresden Bombing was indeed mostly a British enterprise; that's why I mentioned "Bomber" Harris in connection with Dresden Bombing in my earlier post. LeMay's most questionable actions came later when he assumed command in the Pacific.
Clogging rail traffic (in the wrong direction anyway, as evacuating refugees westward would not interfere with transporting troops eastward, as the railcars had to make round trips) is not nearly good enough reason to kill over 100,000 people. It's no more valid a justification than killing POW's in order to avoid feeding them (like Japanese did) or exterminating civilians in order to avoid feeding them while driving them into enemy camps to cause hoped-for logistic difficulties for the enemy (like Nazis did) or mass killing civilians to stamp out partisan fighters (like Nazis also did).
War is indeed hell. That does not mean a war already started, especially to which the outcome was already certain (by 1945 it certainly was), should be waged with maximum hardship to civilians. What was done to Dresden was simply ineffective; ending up stiffening German resistance instead of hoped-for weakening. That made it rank up there comparable to the London Blitz and the Rape of Nanjing. Those "shock-and-awe" campaigns against civilians almost always backfire in the modern age, unlike the barbaric ages of the 12th century.