Too much of any one nutrient is harmful to the body, no matter what it is. Even protein. That's why a balanced diet is the most recommended. Whenever increasing proteins it's always recommended to also increase crude fiber to help in metabolizing the rich diet of proteins. Chickens aren't much different than humans or any other animal in regards to a high protein diet...those kind of diets are usually given for humans or animals that are doing some high performance activity such as exercising frequently and strenuously~hunting, racing, etc., for dogs and horses, high production~milking production for cows or putting weight on beef for slaughter, lifting weights, athletic competitions and training in humans. Feeding these types of diets when there is not a need for that type of energy food can cause stress on kidneys and the cardiovascular system.
If commercial chickens laying at an optimal rate, non stop for a year and a half, can do all that on a balanced ration of 15%-16% protein, any backyard flock can thrive on that also. It doesn't follow that higher protein will give a higher egg yield or better health than the protein amounts to be found in a regular laying ration.