Bear in mind that the term comes from "utopia," which was always an imaginary construct. The original idea was that dystopia would be an equally impossible/imaginary negative society counterpart to a utpoia's impossible/imaginary positive society.

It would probably be most correct to say that societies can be "dystopian" but never "dystopias," because of that part of the definition, but I think we're at a point where that's splitting hairs somewhat.