it protects the skin from absorbing water,which makes skin more susceptible to infection. In some instances it might be good for an area of skin which is rubbed, to avoid chafing.
I prefer it:
I find the unscented vasaline a useful product & recccomend it as a protective barrier on the face & chin of teething babies.It is close to natural skin oil in its protective qualities.
In general, oil soluble creams are great moituruzers. However, they tend to make skin look oily and stain clothes. Most people use water soluble creams during the day. Vaseline would be good at night.