Here's the thing. They aren't bad. Not for everyone.
If used properly, your hair can thrive. I'm not saying every head will thrive, but it's just like anything else.
If you misuse keratin protein, what's going to happen to you? Messed up hair. Also some people's hair doesn't like keratin protein and however they use it, it just doesn't work for them. Petroelum/mineral oil... same thing.
The person with the longest hair on this board oils her hair with melted vaselineI think her hair is thigh length?
The reason many people don't use it is because it creates a tough to get through film on the hair. This film can create a waterproof layer over time, which stops moisture from getting into the hair. If you have petroleum/mineral oil build up, conditioners won't work well, leave ins won't work well and you won't be able to properly moisturize your hair... your hair will get dry.
Natural oils are washed away much easier while still providing shine and "sealing" properties.
With that said, I don't use petroleum personally, but there are many people who do and can use it and have healthy hair. You have to decide for yourself what is good for you and what works in your hair.
Imo it's generally bad if:
You use multiple products with mineral oil/petroleum
You use a leave in product with mineral oil/petroleum daily
You use mineral oil/petroleum and you don't use a strong enough shampoo to get it out of your hair
Even so, some people do ALL those things and have a great head of hair
Tiffers stands out in my mind because look at all her pretty hairand she swears by a product that has a good amount of mineral oil in it.
Do your research, make your own decisions
