You can use the function for example for the fallowing example
your company provides user guides and admin guides for different clients. Some users have an access to space A, some to space B and you don't want to allow users to see each other profiles.
Because user profile contains full name, email, some user activity information (phone optional, location optional) and you want to isolate users of client A from users of client B, in one Confluence.
In this case it's about custom profile visibility rules.
With this function any user is able to hide his profile from everyone.