Originally Posted by tore

That was sort of my point. None of the points you mention are unique to prog rock. Fantasy elements are abound in metal, classical music for example has very long songs, folk rockers have been playing around with old instruments, concept albums can be found in most genres .. and theatrical performances, although it's not something I think of as typical of prog, is also found in other genres.

The point is that a band is prog when it falls within a certain range of possible combinations of certain musical characteristics. That's how useless genres are sometimes. You telling me that a band needs to possess "some elements" in order to be prog only confirms what I wrote.