You are a large network of inter-dependent processes and all of them have to work. Of course this is an absurd example. You are a system of biological parts, not computer components. But most everything humanity has built over the last thirty years or so is dependent on computational parts. And the parts we most rely on are systems of inter-dependent processes.
Power plants have complex computer control systems.
One or two pieces overlooked really could bring down the whole power plant. Power plants themselves are inter-connected. One power plant going down can take down its neighbors. That is particularly true if the neighbors just happen to be having their own computer problems at the same time and are vulnerable. The whole grid winks out.