Comment by pwg

> why there should be an issue with everyone knowing your SSN, or it being in plaintext everywhere

Because far too many businesses, esp. financial ones (banks/credit unions/etc.) have also incorrectly used it as a password to authenticate that "voice on phone" is really John Q. Public and/or that "grifter in chair across desk" is really John Q. Public. I.e., they used the fact that "person X" knew number Y as proof that person X was really person X.

We can argue that it was never intended to be used this way (a true statement), that knowledge of it provides no such proof (also true), and that using it as such was always wrong on the part of these businesses (also true), but the fact is, many did use it this way, and, sadly, many still do use it this way. And it is this misuse that is the "issue" with everyone knowing everyone's SSN.