MCUs are getting crazy. ESP32-S31 running Linux. 40MSPS/12b ADC+DSP on dsPIC33A. New Renesas parts running a 1GHz. RP2350 roflstomping things with PIO. The Cortex M7 in this story is actually pretty old now: circa 2019.
I was surprised seeing a 500Mhz MCU in the iRig. That seems seriously overpowered for what it does?
It depends. This product is pretty niche, and when a ~$3 MCU gives you the headroom you need without a team of career engineers on the payroll, it can make sense. Also, it's running USB power as opposed to batteries.