Or there are plenty of other things you can say about the matter -- it did ask for only one advantage. The command-line interface is more flexible (or "powerful") in that you can easily do operations on multiple files, or on other data you just type into the terminal window after typing the command; and you can more easily specify options -- for example, the 'submit' command would be more cumbersome with a graphical interface, given all of the options.
Whereas the graphical user interface "facilitates experimentation", as we discussed when discussing graphical user interfaces; it looks nicer; you can spend all day changing fonts and colours for everything (you could argue this as either an advantage or disadvantage, depending on what you're trying to do with the computer); and so on.