The use cases are obvious. If you check out my test folder on my own installation, you can create and edit HTML, JS and CSS files. If you try to do the same in my modules folder, you will be denied write access. Setting up a folder such that only some specific role(s) are allowed to view its content, effectively password protecting parts of your content – Is obviously also easily accomplished. Just try out to see the contents of this file, and you’ll see how you are denied access to even read it. If I visit the same link, I of course have full access to read its content. Sending links to clients and colleagues, to specific files in your own CodePen server, is obviously easily accomplished. And sending a direct link to them, for them to see the results of the page, is also obviously easily accomplished.