Not hard to explain, there were clear mistakes made in over-prescription of intensity for the volume of exercise being performed. Was it an oversight? Was it intended to cause pain and send a message? Hard to know for sure.
If it was the latter, the coaches certainly wouldn't be the first or last to try to send a message through prescription of extreme physical exertion. While the practice still occurs and arguably can play an important role in mental-toughness training, it can run counter to physical development and is generally pretty rare anymore.