3 in 1 products

I noticed that my organized brother uses separate products for everything but the messy brother uses 3 in 1 products. I just don't get that! How do you put mouthwash, shampoo, and bodywash all in a bottle? You're essentially drinking shampoo. You're putting mouthwash in your hair. It's healthier and more hygienic to use separate products. He also uses a 4 in 1 toothpaste, facewash, conditioner, and teeth whitening. Gross!