You're not wrong, but there were multiple incidents during the cold war where the US and Soviet Union came very, very, very close to a nuclear exchange, and it was only dumb luck (and sometimes the heroic actions of individuals who were in the right place at the right time) that saved us. We were lucky, and luck is not a plan.
The unwillingness of people to start a nuclear exchange is exactly the plan. In the examples you speak of, common soldiers and technicians refused to launch the missiles. It's noteworthy that the idea of a full-scale thermonuclear exchange is so horrifying that even soldiers who assume they are already dead and have orders to launch still refuse. I think that speaks a lot about the inherent goodness of humanity, but that's a different story.
I know it came very close, but the assumption was that it would come to the brink yet nobody would want to go through with it and begin open aggression. Seems dubious and risky, but once again it worked. And let's not discount the negative risk--a conventional world war with the Soviet Union, China, the US and Britain would have been so terrible.
With such a small data set we should still be dubious, but I don't know if we can consign it merely to luck. I think it was a good plan. Terrible publicity, though. Nightmarish. But so is war.
