> and the average songwriter isn't making data-driven decisions on how to settle on the chord structure for their song

aren't decisions like that implicit to the source of learning/inspiration? it's not data-driven on the surface of the writers awareness, and maybe not data-driven in the statistical sense, but "intuitively", "that which sounds good successively", is based on what one heard so far within the context of the song ... so it's one hundred percent data-driven, just not data that one has consciously quantified.

IMO: average songwriters and musicians and producers are the top exactly because they hit exactly that big fat belly of the bell curve/ G distribution ... I'd say you have it backwards... there's much more experimentation and less data-stuff going on left and right of the average