In 2022 Arduino has several baords, many of which are NOT using atmega 328. Some of them have multi-core Arm chips, some of them have risc-v (not sure if they have any of those as multi-core though).
There are already people running FreeRTOS on those.
Not sure why you would dismiss multitasking on those as "useless".
Even on an AVR, you can implement lightweight cooperative scheduling with low resource consumption. That gives you many of the benefits of an RTOS with less risk of creating heisenbugs. Arduino should have broken free of its main-loop architecture long ago.
There are already people running FreeRTOS on those.
Not sure why you would dismiss multitasking on those as "useless".