Part of it is that there's a public risk with this sense of 'preparedness'. If large amounts of people feel comfortable with nuclear war breaking out because t

Part of it is that there's a public risk with this sense of 'preparedness'. If large amounts of people feel comfortable with nuclear war breaking out because they have their bomb shelter stocked in the backyard that poses an existential risk for everyone. While people may overestimate the vaporization radius of a specific bomb we definitely don't want a larger underestimation of the affect of large scale nuclear conflict. This was kind of the point of the pugwash conference, to remove nuclear weapons from political escalation more generally. If we're not successful at this and it escalates or becomes political that might be the end of it. “In view of the fact that in any future world war nuclear weapons will certainly be employed, and that such weapons threaten the continued existence of mankind, we urge the governments of the world to realize, and to acknowledge publicly, that their purpose cannot be furthered by a world war, and we urge them, consequently, to find peaceful means for the settlement of all matters of dispute between them.” https://pugwash.org/1955/07/09/statement-manifesto/ https://pugwash.org/1955/07/09/statement-manifesto/