Note that the wiki is community maintained, if you think that things should be updated feel free to contribute.
Also note that for quite some time, catkin_make
automatically initializes the workspace if it hasn't been initialized. So there is no need to explicitly call catkin_init_workspace
anymore (not exactly sure when this change happened). I still find myself calling catkin_init_workspace
manually mostly out of habit, and it certainly doesn't cause any problems. I think you are referring to this tutorial, which works perfectly on my machine.
See this question for more, or check the catkin_make source code that actually initializes the workspace if required.