Is there any place where I can change this behavior, so a user can't see everything in /stuff unless they knew the name of a page there? Sometimes, I don't have any reason to put an index.html file in every folder.
It's matter of putting an Options directive in your .htaccess file. If you do this at the root level of your domain (inside the example.com folder), it will prevent directory browsing in all of your directories.
Thanks for finding that article. I will try this when I am at home.