That only pertains to glycerin. Other humectants don't do that. I live in the arid Southwest and because I have coarse low-porosity hair, I need to use humectants. However, glycerin makes my hair drier because it takes moisture from the hair and gives it to the drier air.
3b/c, medium-coarse, low porosity, low density
HG: Jessicurl Too Shea and Kinky Curly Curling Custard
Shampoo: nonsulfate shampoo and Suave Naturals sulfate shampoo when needed