Why is there a conditioner for the Plantur 21 #longhair Shampoo? Doesn’t the Shampoo contain sufficient conditioning agents?

A shampoo is primarily meant to clean the hair and scalp. After washing, the hair’s scaly layer is not fully closed. A Plantur 21 #longhair Conditioner​​​​​​​ closes the hair and provides it with optimal shine and excellent combability.