Keith Jarrett is one of my piano heroes :)

The conventional way of learning piano has a student learning sheet-music pieces that get increasingly difficult as the student improves. It's a fairly linear path, and the vast majority of students will never be able to play a difficult piece like, say, Chopin's Fantaisie Impromptu, as well as a top performer.

Similarly the vast majority of students going the chords/voicings/improvisation route will never be able to play Over The Rainbow as well as Keith Jarrett, but they can at least have the satisfaction and enjoyment of doing it in their own unique way.

Composing your own music takes it a step further again.