What's the point of wrapping hair in a towel when I use any hair treatment for my hair?

I read several times when people use any hair treatment (oil or cream), they usually say wrap the hair in a towel...is this necessary?? what does it do exactly coz I usually put the oil or cream and leave them on without wrapping my hair in a towel..what's the point??


And should it be warm?? How can I get it warm??What's the point of wrapping hair in a towel when I use any hair treatment for my hair?
the towel makes the treatment more locked in with heat