You'll forgive, perhaps, my insolance in asserting that "Air Traffic Control" is a misnomer. Obviously ATC has no mechanical or electronic control of an aircraft, but has the responsibility to provide a path clear of hazards to the aircraft's destination, and provide appropriate communication.
ATC also has alternate procedures for loss of contact with an aircraft. If a flight "goes dark" for whatever reason--intentional or not--it becomes a hazard to other aircraft, and ATC must follow those contingency procedures.
Do I have it right?