If I only used products on my body and in my home that were specifically designed for the purpose, and only ate food that specifically evolved for me to eat it, I'd be in serious trouble.
Hen's eggs are for baby chickens, honey is for a bee colony, baking soda is for raising baked goods, vinegar is for preserving food, oils are for nourishing plant seedlings. All of these things have alternate uses, in fact all of them people on NC.com use on their hair.
There are many similarities between the formulas used for shampoo, shower gel and dishwashing liquid, between the formulas for hair conditioner, a lightweight body lotion/ milk, a face cleansing lotion, plenty of girls use conditioner to shave their legs or as fabric conditioner, plenty of people with skin conditions like eczema use a cream not a foaming product to cleanse their body.
Really someone who has studied beauty therapy should know about ingredients and formulation but sadly the science they are taught is quite low level, at least here in the UK. It's much like the average hairdresser knows nothing about caring for curls unless she has curly hair herself. I am 40+ with 2a hair at the back and 2c at the front, not one single hairdresser over several decades ever noticed that I have anything more than a few little kinks and waves! My skin is the same: I researched skin structure and the ingredients in my own products, I successfully treated my atopic eczema/ contact dermatitis, not a doctor or beautician.