Interesting notes (as usual) over at Hotel Point. I had been thinking vaguely somewhere in the same general area this morning.
That is, about how poetry is an art of modulated speech flow. Something like learning to play the flute or another instrument. There's a level of diction, meter, rhyme, etc., just as there's a level of technique with the instrument. Then there's another level combining fitness & invention, which is maybe somewhat similar to composition. (I know what I'm talking about, having studied piano from age 6.)
(Obviously these are not new ideas - just basic ideas.)
Maybe it's the notions of fitness (these days, anyway) that vary more than any of the other factors (from poet to poet).