I don't think it's collagen that my lips lack but sebum. Sebum is what keeps skin waterproof and elastic. Alot of people on here had been on Roaccutane for severe Acne when I first started posting which interferes with the body producing sebum and also creates dry lips.
A lot of people on here also have Fordyce's Spots which are to do with sebaceous glands. My top lip which peels has a number of these white dots right across the peeling line. My bottom lip, which doesn't peel, has none. I don't believe this is a coincidence.
I still think that the white dots are hardened sebum in the glands which blocks natural sebum from reaching the outer part of the lip. This prevents the skin from ever stretching or repelling water.