It is encryption, but not very convenient. You forget that there is one important use of encryption, and that is in military operations. A one-time pad would be a good choice in this situation---you give soldiers who need to receive encrypted messages the keys on paper so that they can be teared and destroyed, one by one. For each message, you take the next key, decrypt the message, and then destroy the key so it's never used. Of course, if they compromise the keys on any end, it's game over, but mathematically it's as secure as it gets.