> They are (or were) refusing to provide any indication to those other companies that these are not, in fact, the same people
That is not quite true, the sub field will be different.
That is not quite true, the sub field will be different.
https://support.google.com/a/answer/33314?hl=en&co=DASHER._F...
To me it is reasonable that orgs may want to eventually reuse an email address on a different user account. That's a feature decision made by the IdP so SPs need to respect it. I believe other IdPs like Okta and Entra have equivalent features too.
I think everyone, including the authors hopefully agrees with that logic and sentiment. And that would be the literal point of the sub claim after all!
But the implication in the article is still, as i read it, that it changes in place in practice, and not in the case of re-creating the user under the same workspace. But i obviously do not have the background to clarify!
If by "same people" you mean being able to tell whether a new user is part of the same organization, the sub field is useless and no other field has this information either.