Step 12 of this Lab includes the following very misleading statement:
"A hard link protects against accidental deletion of the original file and keeps the backup file updated as you change the original file."

All references to "backups" should be removed in hardlink discussions. A hardlink is not a backup. There is no duplication of data at all. Let's not mislead people into thinking that hardlinks provide some kind of protection. Create real backups to protect your data.