Composers of the past as performers
One can easily imagine what degree of freedom composers of the past, like Mozart or Beethoven, could haave in performing their own music. If we could, with a magic wand, bring them back to life, today they would probably be in trouble. They would have to acknowledge, and come to terms, with a performance practice of their own works that has developed ever since, over about two centuries. It is a tradition they knew nothing about, because it did not yet exist. It is a tradition no one can afford to ignore. We will never know what the music Mozart and Beethoven sounded like to a public that could not make reference to a performing tradition specific to it. Maybe that is why recitalists today can only hope to achieve visibility and fame, by practicing the canon. The canon allows the public to experience performances in relation to a tradition, withing a frame of constraints and listening experiences that make evaluation and judgement easier to formulate.