"Russia and America created any sort of deterrence at all against conventional land wars, in spite of the fact that we have many decades of land wars showing otherwise."

But none of those land wars were remotely like World War II in the amount of worldwide death and destruction, loss of treasure and the complete disruption to everyone's lives almost all over the planet. You know what a U-boat was I trust? How about a firestorm created by bombing? There was fighting in the Arctic, and in Borneo. Even the present war In Ukraine is like a single regional campaign on the Eastern Front in scale, one that only a real WW II buff could even name. If you took all of the land wars that have happened since WW II, it still wouldn't equal the carnage of that single war.