Comment by attractivechaos

Couldn't agree more. Advanced piano pieces often come with nontrivial cords and multiple voices. Those without proper ear training can hardly recognize even a single cord, let alone replicate a whole piece just by ear. Genius born with perfect pitch may do the magic without training, but they are extreme outliers and their experience can't be generalized to the wider population. For most people, inability to read music will severely limit their reach in future.