You're right that it wasn't intended that way, but it's incredibly incompetent of them to think it would work that way. They discarded the idea of using names/

You're right that it wasn't intended that way, but it's incredibly incompetent of them to think it would work that way. They discarded the idea of using names/addresses to identify people because it was unmanageable, so how did they propose people authenticate to these systems if it wasn't via SSN? I.e. if your SSN is a UUID, then what's the password to authenticate into these systems? Your name? That's even less secret than your SSN. Your address? Historically and today, if you want to update the address your checks get sent to, you can send them a letter with your name, SSN, old address and new address. One of those obviously has to be a secret, or anyone can reroute your SSA checks wherever they want. Which one of those is meant to be a secret? Names and addresses are void due to phone books, which only leaves the SSN. That means the SSA is using SSNs as a personal identification document, regardless of whether they claim it was designed that way or not.