As pilots, we train to fly our aircraft safely and efficiently using the primary controls at our disposal. This includes the flight controls and the engine controls. Losing a primary flight control can have devastating results, and so a great deal of emphasis in aircraft maintenance is placed on proper maintenance and functioning of those systems. However, the loss of a primary engine control (throttle, mixture, or prop) can have equally tragic consequences, especially over inhospitable terrain or at night.
Source: aopaAircraft Maintenance: Engine control cable failures