Why would a two in one shampoo and conditioner ruin my hair so horribly?

I used to use one of those and I figured because there was a mix of so many chemicals, herbs, oils, and extra things like for smell and color, that it just wasnt the right mix and therefore it ruined the texture and it made the ends of my hair reaallly weak.Why would a two in one shampoo and conditioner ruin my hair so horribly?
The mixture of oils and harsh chemicals that help shampoo and conditioner mix make hair more vulnerable, so I suggest not being lazy and doing it one at a time. :)


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