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).