This has been bugging me for a while, actually. You see those ads for things like Pantene Pro-V (with VITAMINS!) and skin lotions with Vitamin E. As I understand it, besides your hair and the outer layer of skin being dead already, vitamins aren’t really any use topically. They have to be metabolized to work, right? So the vitamin shampoos and skin lotions don’t actually DO anything that non-vitamin versions don’t do, right?
I’m not promoting these things but I do have a problem with some of your reasoning. For one, most forms of vitamin E are oils and oils can certainly have an effect on hair and skin. They may not be working on a systemic level, but there is no necessary reason they can’t work on a topical level. Whether they do or not is a separate issue, I just wouldn’t be so quick to say that it couldn’t possibly happen. When it comes to my body, I’ve learned to try things and see what happens.
I have a friend that has amazingly beautiful gardens around her home. When I asked her how she does it, she said, “I try lots of different plants in different locations. I keep the ones that work and discard the ones that don’t.” Simple advice, but it seems to work in many situations.