I have a place to leave messages that is with in minutes walking distance of my house were I can leave messages for my wife or she can leave them for me that is not obvious to anyone else. This is in case we get separated during an emergency and there is no house to go back to or it is red tagged so we can’t use it. We will still have a private “bulletin board” to contact each other.
If all the phones and other utilities are down having a contact point can be critical. As an aside you should also have a place to meet in case of fire at your house so you will not go looking for some who is already safely outside. Kind of the same idea for the drop.