Just as unique is the jazz rhythm section. The music demands the highest virtuosity. Yet there are no absolute standards of excellence. Art Tatum's fulsome piano technique has drawn praise from classical pianist. Then you have Jimmy Yancey, who played only a few tunes in a few keys but distilled the last drop of feeling from the blues.
Jazz can be worth performing at any level.
There are also no absolute rules about how one should sound. Thelonious Monk was once described as treating his piano as an unexplored instrument. Coleman Hawkins and Stan Getz are undisputed masters of the Tenor Saxophone. Play a representative solo by each, one after the other, and you can hardly believe that the same instrument can produce such an utterly different tones. As jazz changed, diatribes against each change, and diatribes against those who oppose change, have led it to rival the Christian Church in the number of its schisms.