'Nourishing' the skin and hair

I hate to see claims that are made about various skin and hair products which suggest that the vitamins, etc that are within them can 'nourish' skin or hair. Can it be proven scientifically that these substances are actually absorbed by living reproducing cells? First and foremost, that visible hair we have is dead. Absolutely dead. Next, the visible skin that we have is dead too. What can feed the dead? Our skin is designed to hold what is good in, and keep what is bad out. The wonderful stratum corneum can be breached selectively, however, and here is a good description of various compounds which do this: http://ijsidonline.info/admin/pdf_files/REVIEW%20ON%20CHEMICAL%20PERMEATION%20ENHANCER%20USED%20IN%20TRANSDERMAL%20DRUG%20DELIVERY%20SYSTEM.pdf
I found the essential oils listed to be of particular interest, since I am on the continuous quest to live better without pharmaceutical intervention. Yes, good old sodium lauryl sulfate is on this skin breaching list too. I have discovered that my life is better without applying products which contain this substance. I do not think that the natural soap that I make disrupts the structure of the stratum corneum or any other integumentary structure in any way, and I like it like that. I base this thought on the remarkable decrease in dry skin and acne that I have enjoyed since I quit using commercial products and began making and using my own soaps. However, since sodium lauryl sulfate does affect the stratum corneum, then perhaps those vitamins, etc in products made with it could actually penetrate to an active cellular level due to it's effects if the product was left in contact for a sufficient length of time. Ironically, the safety of sodium lauryl sulfate depends on it not being in contact with the skin for a sufficient length of time to cause harm. Look that up with the FDA. So-what's the good in combining these substances?