The backlog is probably in the area of making sound
judgements
(especially in deciding whether or not to delete). This can be done
without adminship at all, though.
That's an interesting point. People seem to miss that there is more to
adminship than the technical admin tools. Closing AfDs is an admin
power, being automatically whitelisted on most vandal-fighting tools
is an admin power, being able to reject unblock requests is an admin
power, etc., etc. Just because they are explicitly included in the
$wgPermissionsGroup['sysop'] part of LocalSettings.php doesn't mean
they aren't admin powers.