Like the woman who posted that, I also believe water is the only thing that can truly moisturize hair, however my opinion is that there is nothing wrong with using other products like the ones listed on your hair, as they are used to enhance softness, strength and manageability which water only cannot provide for alot of people.
Btw, I have tried water only and my hair was duller, more porous from washing too frequently (hair started feeling odd. Its hard to explain the feeling but it was strangely gunky feeling, like it was rubbery or something), and it was even more rough than usual after it dried. I'm back to using products on my hair now and I'm never doing water only again. It's a majorly underwhelming technique in my opinion (from my experience).
The bolded I believe is called hygral fatigue.
Here's some info I found on it:
What Is Hygral Fatigue?
After digging in a bit deeper, and not finding a dictionary definition for hygral, I came across the word
hygrometer, which leads me to the terms hygral and thermal property in a
NASA study and in a
book about textiles. This was when the fog came clear and things started to make more sense.
Damaged Hair Cuticle
When we wet our hair it behaves very much like a dry sponge since it absorbs water and it gets swollen, bigger and heavier, and then dries out to return to its original shape. This hygral property of the hair to absorb water/moisture puts a strain on the hair’s fibers as they are constantly swelling/expanding as the water intake increases, and subsequently contracting when the hair returns to its original water content (dry).
Similar to a rubber band, when these specific movements (expanding/contracting) are repeatedly done the hair starts to lose its elasticity, and is then in hygral fatigue. In other words, the hair is worn out! The cuticle layers of the hair and the cortex are weakened and this can lead to breakage and increased
porosity. This is obviously something we all want to avoid.