I've heard very few people who play totally by ear that do a good job. Most miss some of the chord changes, play a F chord instead of a Dmin7, and have no clue what an augmented or diminished chord is. Three chord country or Louie Louie type R & R may work OK for the ear player but let's hear them play "All The Things You Are" or "Wave". My teacher made me play by music, chords and by ear. I think that was a good combination.

Tom