Oh, I agree that the big-band trend would have gone away anyway. It was also extremely (prohibitively) expensive, having all those sidemen to pay. Indeed, another thing is that by around 1945-46, a lot of the jazzier bands starting veering in the direction of more of a be-bop sound, which has its afficianados, but the general public just never warmed up to it. Same time, some of the mainstream/hotel bands seemed to go in the other direction, more sweet than swing.
Not much middle-ground for the public, which probably found some bands either too harsh/abrasive in the be-bop jazz vein (and bands like Stan Kenton were always an acquired taste), or too syrupy/mellow, referred to as mickey-mouse bands in the Sammy Kaye mold. The “swing bands” of 1937-42 were hitting a happy medium of hot and sweet, and that’s when they attained their highest popularity.
That was always my understanding. Not only were there all those salaries, but the travel expenses of touring with a large outfit. Guys like Louis Jordan were figuring out that you could get a big sound (and fill a dance floor) with a smaller combo, and you could put them all, with instruments, into one or two cars.
