I actually agree with everything you say, but that doesn’t negate my points! Yes, sometimes a melody will suggest certain chords. Take a tune like The Soldier’s Joy: in the first bar it’s practically impossible to play anything other than D major (the melody notes being A, F#, D, F#, A, F#, D, F#, A, D, D), but with the second bar ending with crotchets G, E,E, do you play Em , A7 or something else? (I’d be more likely to play A5).