It would imply that the author knew every possible value or was willing to continually track and update his creation as other projects introduced new options. In the example you chose, I'd expect the string to be compared against a similar string in the target platform. Implementing a selection box would potentially hinder adoption on different platforms. This option would likely end up as a freeform text field in any GUI, resulting in very little gain. Providing a GUI also implies that the application is being configured somewhere that the GUI can be displayed. It may be 2020, but many servers are still handled remotely via the CLI, because it's generally sufficient for task at hand and an efficient use of resources on the target server and bandwidth. Further more, the authors skill set or time available may not extend to developing a GUI and documenting the app. If the choice was between a configuration GUI with options, but no documentation to tell you what they meant and no GUI, but sufficient documentation to allow you to take a stab at configuring in a text file, which one would you choose?