Even Boris Vallejo must abide by the rules.
On a related note, does anyone know if Vallejo is the artist behind Heavy Metal?
His stuff is not merely unrealistic; it's impossible. Even those who create fantasy have to stay within the bounds and rules of their own creation. Otherwise it is all meaningless.
He has a couple of cheap tricks with light that he has run into the ground - tricks that were known long ago and have been used better by people who actually understand light, perspective, anatomy, botany, etc. What you see as "beautiful" is merely a conjuring trick. Others do it better, and can actually paint.
It is irrelevant whether it is possible or not. The meaning is in the warm feeling it creates. That's real. Talk to the collectors of his art. Observe the smile on the faces of people who view his collections. Something real happens to them.