You know the saying, "what's 'all-natural, organic' today was just business as usual a hundred years ago".
Therefore, the question of ditching chemistry-set shampoos may be to look back into how they used to do it.
No, I'm not clever
enough to have added that up for myself, but I just saw a youtube
video by a history buff. She's primarily into clothes, but she has turned her difficult, curly, hair into waist-length, all using natural, historical, "poo-less" methods.
Pretty impressive. If you try it, post back. I'd be curious to hear if it works.