Can the timing chain jump when turning the engine off or on?

Recently my ute wouldn't start after driving fine the night before. My mechanic ran diagnostics but the computer wouldn't produce any fault codes. He sent it to an auto electrician who said immobiliser needed replacing so I did that but still wouldnt start. Sent it back to mechanic who is now saying the timing chain has jumped 5 teeth and I need a new engine. It just seems odd to me that if valves, pushrods etc bend and break when timing chain jumps why was the car running fine all the way home then suddenly wouldn't start the next day?