>I suspect focused, attentive listening only makes up a small minority of the total streams

The inverse is likely true with the classical audience. Just like with jazz, although there will be a portion of users seeking “vibey jazz” sort of playlists to use in the background while working, the majority of jazz fans consume jazz as albums and are still concerned with things like personnel and liner notes, perhaps even who mastered this recording. Classical fans are similar except I would say even more picky IME (worked in a jazz and classical CD store/venue for a number of years)