I disagreed with GUEST's statement "At the end of the day, all any song is is a sequence of chords and words", whereupon (presumably the same) GUEST responded "Notes almost always form arpeggiated chords, barring the odd passing note or elision."

That is still not true.

Of the kinds of folk music with which I am familiar, the kind that has the largest proportion of arpeggios in the melodies is Swedish; and even those melodies are by no means only arpeggios, also including scale runs and some phrases that are neither. Other kinds are even more of a mixture.

Coming back to British/American/etc: some phrases strongly imply particular chords, insofar as one wishes to use a chord at all. Other phrases can be chorded in various ways. Some tunes fit standard chord sequences, in which case there is a good case for using those sequences, especially if several musicians are playing together. But if you're on your own there's usually some flexibility, and sometimes a lot.

And, as I alluded to earlier, on a one-row melodeon either you use the single chord that's available with the current direction of the bellows or you do without.