A number of my clients have multiple WordPress websites. They write their own content. Sometimes they want a play area (AKA sandbox) where they can try things out without messing up the site content.
For quite a few of them, implementing a WordPress Multisite solution would appear to be the way to go.
They would have their main sites visible to the general public and the play area(s) would be protected from view.
But it’s not just a simple matter of creating a site which is not checked as Public.
Although it would not be listed by a shortcode such as [bw_blogs] it would still be accessible if you type in the site’s home URL.
So we need a plugin to protect the site. There appears to be a choice.