Hello,
I hear your points, certainly.
If adding listing or the authenticity of the users should be restricted beyond what GD offers a membership plugin will be needed. We offer UsersWP https://userswp.io – which allows a site manager to use an addon and manually approve/verify users on the site.
With the current version of GeoDirectory, users must register for an account before they create a listing. Some users will no doubt fall out of the process and fail to complete a listing. With GeoDirectory V2 it is possible to see in the WP Users (list of all users) which ones are the owners of listings (and how many) so this will make it easier to remove users who don’t have a listing if that is the objective.
With comments and reviews there is a bit more flexibility because WordPress itself allows site managers to decide if users must register. In the case that users ust register to comment/review then we have available the Re-Captcha Addon to prevent bots from registering and to cut down on bot spam. In general the idea for allowing anyone to register is to get users to create a profile and add comments and reviews on listings and showcase their list of reviews. In this case these users won’t have a listing.
Hope that helps 🙂 And it you have more questions about GD security, just let us know.