I do think that it's a really posibility that EC is a form of Seborrheic Dermatitis at least for some of use. I also have it on my sculp and have for a few years. The area around my lips also builds up and even crusts, even down to almost my chin, so last year I used a shampoo used for sculp SD on that area, and it got better for a while. I'm not sure if it was just the shampoo cleaning the area and therefore getting rid of build up skin, but it may just have been the ingredient helping.
Maybe in a few months or so, when "moist healing" hasn't shown any progress, I might try using it on my lips as well.