It's OK if the photographer (not digital artist) provides the truth in the description accompanying the image. Then, it can be taken for what it is -- a work of photomanipulated art (photographs are works of art in their own right) -- but it lets the viewer know where reality ends and fantasy begins.
I've seen a lot of it on Facebook/online, where the Milky Way, for example, has been exaggerated and transformed and rotated to suit the composition and the author hasn't stated as such. It is great for what it is and is a representation of the artist's creative abilities as well as vision. But, amongst the viewers are people who are interested in photography and want to try their own hand at capturing the night sky. Seeing grandiose images like that does nothing but deflate their enthusiasm when they try it for themselves.
Then again, all you need to do is pump the saturation to 100 and beyond, to the point where posterisation (blocking) occurs, and you'll have an instant winner.
H