When could it be useful to have a device turn off completely if one part breaks?

It could be useful for a device to turn off completely if a critical component, such as a safety sensor or power supply, malfunctions. This prevents further damage, protects users from potential hazards, and ensures the device does not operate in an unsafe state. For example, in medical devices or industrial machinery, a complete shutdown can avert accidents or health risks. Additionally, this feature can enhance the longevity of the device by preventing cascading failures caused by a single broken part.