Hi Spalding
Nobody is denying that if you spent enough time and had creative talent that you could make great music on an arranger, the questions is “Why” when there are so many instruments out there better suited to the job.

The truth is; the Arranger is and always has been designed to allow one person to emulate Orchestras, Big Bands etc., in a domestic environment with minimal work, nothing more, nothing less. (That pros can make a living with them just shows how versatile they are)
Regards

Bill