Configuring staged users to watch categories and tags is a way to sign them up to get many emails. These emails may be unwanted and get marked as spam, hurting the site’s email deliverability. Users can opt-in to email notifications by logging on to their account and configuring their own preferences.
If staff need to be able to configure these preferences on behalf of staged users, the “allow changing staged user tracking” site setting can be enabled. Default is to not allow it.