Last year there was an article posted here about how tax policy on live performances killed big bands and dinner clubs. I wonder if that law was related.
How the Taxman Cleared the Dance Floor (How a 'cabaret tax' brought the decline of Big Band Music)
There was also a musicians union strike where they didn’t record (I think around 1947) and BMI started gaining ground by recording hillbilly and “race” records (genres which ASCAP refused to publish).