SQLite is known for implementing its database as a single file, whereas other databases use multiple files. Likewise many applications condense their files / filesystem into one file that they read with offsets instead of accessing multiple different files on the operating system. An example is video games that pack their files into a big archive. In the case of read-only files (ie., no files are going to be modified) and that are zipped at one stage and only read from there on, I see the advantage being in condensed single file archives. This is because fewer system calls to the OS and searching for files to open. You keep a table of indices and just index into the same file stream, or mapped pointer in the case you’ve memory mapped the file.