Postmodernists believe that truth is myth, and myth, truth. This equation has its roots in pop psychology. The same people also believe that emotions are a form of reality. There used to be another name for this state of mind. It used to be called psychosis.
In Modernism, reality used to validate media. In Postmodernism, the media validate reality. If you don't believe this, just think how many times you've described some real event as being 'just like a movie.'
It's my guess that those cutting-edge artists who attack tradition secretly believe tradition will survive to enshrine them as the wild and crazy geniuses who destroyed it