With the idea of the recent HN article that files are the common media of communication between humans and LLM's, it's still useful to have direct file-skills; to be able to read raw files the LLM outputs, or give it input through files, and able to manipulate the files efficiently. You can use an LLM to prompt to search through the files and all that, but for such basic things it's worth learning it yourself, if you do it often.