It’s ridiculous. I have scalp issues too, I’m talking super painful, weeping, scalping etc from dermatitis. It’s not fun, but can be managed so it’s not a big issue outside of occasional flare ups.
First rule, don’t use products full of fragrance, such as that function of beauty crap. You need medicated shampoo and conditioner, with ingredients that will soothe and treat. It’s clear it’s not well managed as you can often see sheets of dry skin in her hair is most of her posts.
It’s stupidly irresponsible to recommend using some nasty ass unsuitable shampoo pretending it treats dermatitis. It doesn’t, it’ll flare it up.
Also, if you have greasy, flat, thin, lank hair (ahem.. Demi) then leave in conditioner is a terrible idea. Why the hell is she using this, or more likely, pretending she does.