Well there's the use case of a device which gathers data and then uses its radio once every handful of hours to report that data to some service. If you're constantly using the radio you're gonna use way more power than my numbers of course.

I also don't think it's too unreasonable to use a C3 as an MCU in settings where a radio isn't required. The IC itself (aka not the wroom module etc) isn't that much more expensive than equivalently specced MCUs without a radio, and if you're already more familiar with developing for the ESP software ecosystem it might well be worth the few pennies extra. The ESP32-C3FH4X (so the IC with 4MB onboard flash, super easy to integrate into in a design) only costs $1.6 per unit on LCSC for 100 units (and mouser etc is similar).