This utility is no more than a toy. Rather powerful toy nevertheless. It was written as a proof of concept to show ability to use almost any appropriate public keys to encrypt data.
Sometimes there appear situations, when you have no other alternatives besides coreutils and ssh installed on the host. Well… If you can install in addition openssl, why don't install GnuPG? I don't know, but this script allows encrypt and sign files using only existing ssh keys with openssl as backend.