The article ”single-sign-on“ has some mistake

[zhusaidong]

The article ”single-sign-on“,
it say "If the user attempts to access another SSO-enabled application, the process is repeated automatically without requiring them to log in again."，
Neglected a premise，The IdP requires a user identifier, such as a cookie, to determine if they are the same user.
Only the same user can "without requiring them to log in again".
This user identifier is the key to understanding why login is not necessary.