Why command line interface more used for developer than GUI

That is a golden line for all Linux or command line interface users,

"The GUI makes easy tasks more easy, while command line interfaces make difficult  task possible."

Here some links which will use to understand command line interface briefly.

1. http://searchwindowsserver.techtarget.com/definition/command-line-interface-CLI
2. http://www.linfo.org/command_line_interface.html 
3. http://paguilar.org/?page_id=17