[themulticaster]

The user you replied to likely means something different: The priority of the event often depends on the exact contents on the event and not the hardware event source. For example, say you receive a "read request completed" interrupt from a storage device. The kernel now needs to pass on the data to the process which originally requested it. In order to know how urgent the original request and thus the handling of the interrupt is, the kernel needs to check which sector was read and associate it with a process. Merely knowing that it came from a specific storage device is not sufficient.

By the way, NMI still exist on x86 to this day, but AFAIK they're only used for serious machine-level issues and watchdog timeouts.

[wizzwizz4]

This, too, can be done in hardware (if nothing else, with a small coprocessor).

[refulgentis]

This doesn't shed light

Generally, any given software can be done in hardware.

Specifically, we could attach small custom coprocessors to everything for the Linux kernel, and Linux could require them to do any sort of multitasking.

In practice, software allows us to customize these things and upgrade them and change them without tightly coupling us to a specific kernel and hardware design.