After decades of improvements in graphical user interfaces, the Unix command line interface still remains the most powerful way to get things done for a lot of workflows. This is due to many reasons: the difficulty of quickly and precisely moving the mouse cursor compared to the ability of touch typists to select exactly what they want (even when it's via hotkey combinations), but mainly (IMO) the expressive power of composing separate Unix commands into one pipe-separated command operating on standardized files (usually text).
It's also easy to write your own Unix commands which...