[Vince]

With this technique, if you want to add a new functionality you have to make edits in twenty different files. This means callbacks eventually become bloated with unrelated stuff and that the functionality is spread out in all those files.

If you have one file per functionality you keep everything in one place. It also means that you can disable the entire system by commenting one include line in the main gamemode. The (hooked) callbacks in that file are clear and concise and ONLY contain the code for THAT specific functionality.