Every living organism is composed of proteins. Next to water, protein make up the greatest portion of our body weight. You can make big mistakes with fats and carbs and correct them easily. But your mistakes with protein build right into your structure, and hamper performance for months.
Muscle is comprised mainly of protein, the more protein you make available to you body, the more likely you will have a better growth of muscles. More available protein helps you to develope faster and aid in accelerating your post-workout recovery.
SIMPLE, YOU CANNOT GROW QUALITY MUSCLES WITHOUT QUALITY PROTEIN.