Using shampoo is important for those with oily hair because it helps to remove the excess oils and buildup that can accumulate on the scalp and make hair look flat and weighed down. When oils and other products build up on the hair, they can cause it to become greasy and heavy, making it difficult to style and manage. Shampoo helps to strip away these oils and leave the hair feeling clean and refreshed. Additionally, using a shampoo specifically formulated for oily hair can help to control excess oil production and leave the hair looking and feeling healthier. Overall, regular shampooing is an essential step in maintaining the health and appearance of oily hair.