If helps if a) you've misconfigured your "office only" rules, or b) someone has breached your office network/one of your local machines (but hasn't discovered any of your keys/passwords yet) and is trying to get into the server. It also helps with non-ssh services too. A belt-and-braces approach. If you accidentally lock yourself out using it, use your out-of-band access to re-enable your logins.