To a casual user, showing a raw file tree seems unprofessional. Why would a developer leave this on?
However, for internal networks (intranets), legacy systems, and open data portals, the Index of page isn't going away. It remains the most bandwidth-efficient, cache-friendly, and universally understood way to share a folder of files. Index of
This command tells the search engine to look for pages where the words "Index of" appear in the HTML title tag. Here are advanced variations: To a casual user, showing a raw file