Not exactly sure where it fits in, but I absolutely adore the documentation provided by most projects in the Unix world. I love being able to --help a program and go searching through manpages for a particular command to find out how to make the program behave in the way I am hoping for. Sometimes, you find out that it can't. Bummer. Add it to the project list of something to do. Or, you find out that there's a few switches that do things you did not know about and now have found a better use for said program. The see also sections of manpages are a good place to check as well. Perhaps there's a program that does what you are looking for. And outside of manpages, half of my bash_history is spent in /usr/share for the various sample files and added documentation.

So I think doing one thing and doing it well lends to this aspect of the unix philosophy because now that the simple program has been perfected, the author can now start focusing on its documentation. Which I greatly appreciate.