Someone else confirmed my recollection, so evidently you won’t need to use the --deploy-hook for this specific purpose with the nginx plugin. (Probably most nginx-related suggestions to use hooks were inspired by --webroot, which used to be recommended for nginx users before the Certbot nginx plugin was working. Since the webroot plugin doesn’t include an installer, it doesn’t have a built-in mechanism to restart the web server upon deployment.)
If anyone has any contrary experience, please let us know and we can try to fix or document this.