Who doesn't have an auto increment Id field on every table? Ok I know its not a 100% perfect solution for a user id.
The other gotcha is using ss on ni numbers as identifiers
The other gotcha is using ss on ni numbers as identifiers
In large organizations with a lot of teams, natural primary keys make interoperability easier across databases, as opposed to a forest of artificial keys that are all different. SQL experts who advocate natural keys point to ON UPDATE CASCADE as the solution to natural keys that occasionally change.
So the absence of an auto increment Id field might be a dumb error, or might be super smart, or might be both. Both means you're a SQL expert but haven't made sure everybody else working on the project always will be.
Anyone who exposes their id fields, e.g via APIs, and doesn't want other people gaining insights into their volumes by watching the rate of increase in id values.
And with former users coming back, of course expecting to have their IDs back too !
This being on a paper-first (often paper-only) database, with no locking process, where we also had the issue of new users being added at the same time, for the same ID.
If only I already had been through a database course at the time…
I think I just proved my point here.