The same kind of backup shortfall and misunderstanding can occur with multisig also, don't see how this is an inherent fault with passphrases.

ANY set up should be tested before using it for funds.

1. Set up wallet with passphrase

2. Put a small amount in wallet

3. *Wipe wallet and then recover from backup

Doing this is essential and will expose any problems with the setup, backup, and or user understanding.

Back up passphrase and seed on separate steel plates and keep them geographically separated if possible.

*Do the wipe and recovery directly from these same steel plates.

You know all this Mr. Loop.