Intuitively that makes perfect sense to me, since young and attractive humans is what people generate most often
If you're looking in the library for books that are at least 100 years old, you're generally only going to see the ones that people thought were worth preserving for 100 years.
If you're training your image generation model with stock photographs, you're generally only going to be giving it images of people who are literally models. Not all models are beautiful, but they're probably more beautiful on average than the general population.
