Exactly...when you're dealing with an instrument that works on discrete note-on/note-off behavior, then the point of actual discrete polyphony enters into things. A good parallel in guitar would be the various complex picking styles of Doc Watson, or the techniques found in a lot of classical guitar repertoire, flamenco/Andalucian style music, etc. Paraphony is more akin to strumming chords and the like, where a single attack occurs more or less simultaneously for all notes, and the result is more of a single sound without internal attacks, modulation characteristics, etc on single notes within the chord.