Giving someone a hypothetical “Restore” permission would be equivalent to making them a Super User. This is probably a non–obvious implication for you. So please allow me to explain.
Restoring a backup requires being able to extract the backup archive and run the restoration script.
The former is really not a major security issue, even though it does raise some security and privacy concerns because the older version of the site may have security or privacy issues. It also raises a practical concern. An end user restoring a backup before Joomla or an extension was updated may end up creating a state with mixed up files from different versions of Joomla / third party extensions which may break the site. Not having full Super User privileges means they cannot fix it.
However, these concerns pale in comparison with running the restoration script. The restoration script shows you the database credentials AND allows you to reset the password of a Super User. This means that anyone restoring a backup automatically gets the Crown Jewels of your site (the database credentials) and can elevate their privileges to Super User. Keep in mind that we are talking about users you do not trust with access to Akeeba Backup's configuration, let alone Super User access. Furthermore, if this user's login credentials are stolen or an attacker otherwise gains access to that person's user account they can now stealthily take over the site just by restoring a backup.
That's why you need the full Configure permission to restore a backup. We make the reasonable assumption that you are not going to grant that permissions unless you REALLY trust that person. If you don't trust them enough to have access to the backup configuration you most definitely should not trust them to restore a backup (and essentially letting them become Super Users at will).
Nicholas K. Dionysopoulos
Lead Developer and Director
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