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.