@Young And Alive
It isn't. Imagine singing a Moz song on your own, voice only; it is perfectly possible. It is still a song, recognisably, despite the absence of guitars, drums etc. Instrumental accompaniment is not an intrinsic element of songs.
As far as Dylan setting the definition of what a songwriter is, I meant that in the context of this thread and the poll.
And I agree that the melodies that Morrissey sings are memorable.
But what came first ...
The melody Morrissey sings ....
or the instrumental that Morrissey is singing on or to ?
You may find that the song dictates/inspires Morrissey to sing the melody that he does,
so again it is a collaboration between the musician that is writing the instrumental and Morrissey.
The particular melody Morrissey sings on a song very likely would not exist without the instrumental music the instrument player is providing.
Yes Morrissey writes the melody but it’s the instrumental music that is inspiring his writing of that melody.
I’ve never heard or read (that I can remember) any collaborator say that Morrissey came to them with a specific vocal melody of his own first that the songs music would be based on.