When a user needs help with a command-line-based application, they usually have two options for documentation: a website or the command-line manual, also called man pages.
Having to locate and read a web page in order to use an application could be considered a lot of hassle, which could deter new users of an application.
Similarly, the man pages within a terminal can be difficult to navigate. It is not intuitive how to search them for a specific keyword and the inability to scroll with a mouse can be offputting to some people.
Within most GUI applications, you will likely see a menu bar at the top. Inside this menu bar can often be found a Help option. This is a rather self-explanatory way for a user to locate instructions on ...