Well, I guess it's basically about that saliva is supposed to have antibacterial properties. Licking the lips without putting anything to add moisture afterwards will make the lips even drier, yea. But putting a good natural moisturizer on them might prevent that. Not sure if it has to be cocoa butter, but any kind of natural moisturizing agent will probably work as well.
I'm not putting all that much faith into that method, but it did sound like it cured at least one person here, right?