I've had some bad experiences with form autocompletion in the past which resulted in orders being delayed (this would have been a few years ago with 1Password specifically), so I always enter address and payment info manually. I assume plenty of people use autocompletion all the time without issue, and will tell me I'm wrong, but that's just my preference.

So memorizing a 7-digit code to enter address information without error seems like a useful feature to me (though admittedly not mind-blowingly so).

It could also be useful in other contexts such as sharing an address with someone verbally, over LINE, manually entering an address into a GPS, etc. Assuming the system actually catches on and the codes are universally supported in map apps.