>Imagine everyone broken their arm at the same time, A+E would collapse, orthopaedics would collapse, any requirement for surgery would be overwhelmed (it is needed in 2 weeks), there would be no ability to get people effective rehabilitation, and people would start dying from complications of broken arms.

Excellent example. The biggest risk with something like COVID are the huge waves of cases that overwhelm response systems. Sure, the vast majority of hospitalized people will survive with some supplemental oxygen, but if you only have enough tanks and masks for half of them the death rate skyrockets.