Without any particular basis for it, perhaps some consideration should be given to the way in which different venues contributed to the evolution of the several different styles(?), and perhaps the venues shaped the music.

The general notion is that the earliest blues probably started with solo performers, (most often guitar with solo vocal?). As the style developed, additional members were added to create small combos, but groups were mostly small as appropriate for little halls.

The similar "lore" is that ragtime originated mainly from the more or less solo piano player. The somewhat more complex structure of the music perhaps required a more rapid jump to somewhat larger combos to move the music to larger halls(?), but it never was commonly played in large auditoriums so far as I've heard. (Although "marching band" spinoffs did appear?)

The primary "swing band" style possibly was deliberately developed for large venues with lots of dancers. The music aside, in the absence of amplification you wanted a fairly large band just to produce enough volume to be heard in a large ballroom. Most of the well known swing bands played from written notation (with breaks for extemporaneous solos(?) written in), and most of the big band tunes were "composed music," more routinely than in the other styles mentioned. Using large "orchestras" almost mandated written scores to keep "most of the players" on the same tune (most of the time).

Jazz, in it's beginnings, probably originated around the same time(s) as Swing, but more likely in smaller (but not solo) groups. It was more common for the "jazz purists" to ignore written scores (because they were hard to get?), if any existed, and play extensively "in free form."

"Purists" through at least the early 50s could become violent over suggestions that "swing" and "jazz" were the same thing, or even that they overlapped even a little bit. Some, at the time, might have said that "progressive jazz" with its odd meters (5/4 or 7/9 time) and polytones (out of tune notes?) was deliberate, in order to maintian the separation.

Just suggestions for consideration - with no documented historical backing that I know of.

In all of this, it should be remembered that written music for the most popular songs could be very hard to get through most of the times when these styles were developing, since the DRM of the eras consisted of prohibiting publication of the profitable tunes. Although now more available, I tried for over 20 years to get any Hoagy Carmichael tunes in written form with zero success prior to around 1965 or so. The only way his widder would turn loose of one apparently was by direct payment to her, for a license for a specific number of performances (especially for Stardust. although he did write some other nice ones).

John