This new breed of star DJ is not content to be hidden away in a booth with a tiny slit, like Junior Vasquez was at New York's seminal Sound Factory. Instead they mosh and crowd surf from their elevated stage, while the crowd look on, shuffling and whooping. Worse still, some of them are alleged to perform to the kind of pre-mixed sets that have caused the Calvin Harris controversy.
Prerecording sets is a curious phenomenon, because it's the live interaction between DJ and dancefloor where the real fun occurs. Without the ability to change the mood, change the tempo, change the style, you're nothing more than a jukebox that needs a toilet break every so often.
It's what makes DJing more elastic and versatile than, say, a rock band, whose members are tied to their audience by the songs they know and have rehearsed.