I read the Aggie's post prior to posting, hence my statement "in addition to the build up from the grease". I am just giving another possibility. Also, when I relaxed sulfate shampoo did not pose a problem for me either. However, there are many who will concur that shampoo (sulfates) can dry out textured hair. This belief was the catalyst for all the no-poo products and co-washing, especially for textured hair.
Referring to the bold, I am aware of the myths, this isn't my first rodeo.
I wash my hair 3-5 times per week as well. I was referring to the use of traditional shampoo on some textured hair.