Jazz constantly spins off new possibilities, seizing on fusion with rock, new rhythms from Brazil and then "world music," astringent harmonies and atonal combinations from "new" music or twentieth-century "classical," and more. [...]jazz musicians have been relaxing constraints since the beginning. Piano players might keep "comping" or accompanying the soloists with well-chosen chords, but they might roam free or just stop playing.\n Again you can wonder how much of this was deliberately plotted out before the trio hit the stage, how much developed on the spot.
Herzog, Donald J. Was That a Song? Mich. Q. Rev. 52, no. 4 (October 2013).