Alert notifications in the automation settings as described here work by mentioning a particular user if an issue abides to the rules set.
More often than not, in case of alert messages, a group of people is required to get informed of the alert.
The current implementation requires each individual user to get added to the rule in order to get the alert notifications. Having the option to add a user group instead of a set of individuals will make administering these kind of rules a lot more convenient and provides a better oversight of the rule configurations.