Quoting Didier Kryn (kryn@???):

> This is the result of enabling devtmpfs when building the
> kernel. Devtmpfs was implemented a few years ago and is, in my
> opinion, a reaction to the bad behaviour of Udev developers.

Plausible.

> For the same reason (explicitly), the kernel now loads the firmware
> automatically instead of requesting it to the hotplugger.

And this _definitely_ seemed to be a reaction to systemd/udev
developers' bad behaviour. I [half-]remember when it happened; it was a
reaction to a specific bit of coder insanity, maybe that kdbus episode?

> Definitely, the hotplugger has less and less to do, and, definitely,
> I think Mdev could do it pretty well.

And simply. You just create a custom hotplug handler script
/sbin/hotplug (the default value of /proc/sys/kernel/hotplug as decreed
in the kernel configuration) like this:

#!/bin/sh
test -n "$MODALIAS" && modprobe "$MODALIAS";
exec /sbin/mdev

However, for my own needs, I personally favour just compiling needed
drivers into the Linux kernel monolithically. (Yes, average desktop
user cannot be expected..., blah, blah, blah.)

I really don't know why so many people think hotplugging is a major
need, anyway. I happily used Linux for a very long time before it existed.