Age would certainly explain it if there weren't many cases of elderly men and women with fine skin (and other benefits from U.T) who attribute it entirely to U.T.
Who knows though, there are many factors that probably play a significant role in the effectiveness of U.T.
Also, youth is not a guarantee of good skin and good health. Just look at early smokers who also have poor diets and poor lifestyles ... they don't look too good.