A far bigger problem that needing to reboot is that
dnf seems to sometimes wack libraries that are in
use and make my X session and/or system crash in the middle of
an update. I never had that happen with yum, but
I've seen it a couple of times with dnf (though I
suspect it may have more to do with systemd linking
in every library on the system rather than being a
tiny "init" program with no dependencies :-).