the basic ingredient will remain effective on the skin for a number of hours, as opposed to alcohol which remains active for seconds (until it evaporates)
in addition the commercial products have scents which also last for hours.
in addition the commercial products are much easier to apply, require no preparation (once you buy them), and require nothing else such as a rag or washcloth for application
you can get generic ones which will actually be cheaper than alcohol, considering the number of applications per container
alcohol is flammable and a potential danger for children
the alcohol fumes can be irritating to the eyes during application