Invite-only Forum - Can non staff members invite others?

Same here, I didn’t really get it but of course, an invite is an explicit approval and users can only be approved by admins/mods.

Is there a case for invitations to be approved? Thus allowing untrusted users to propose invites? Or is this a feature too far?

Perhaps a warning message on the “must approve users” option to be clear that this will prevent the use of invites by members?