Leave-in conditioner does not add moisture to Type 4 natural hair. It seals what is already there. If your 4C curls never absorbed water first the leave-in just coats dry strands and adds buildup without solving the dryness underneath.
This video breaks down the biology of leave-in conditioner and why applying it to dry Type 4 natural hair is the reason your curls feel coated but still thirsty.
If you have Type 4 or 4C natural hair and struggle with dry hair, product buildup, greasy roots, or wash day mistakes this explanation will help you understand what is really happening.
Water it. Section it. Control the tension.