The GNU tar man page is explicitly a shortened reference, because the real manual is in info format. Info manuals are often examples of documentation done well

The GNU tar man page is explicitly a shortened reference, because the real manual is in info format. Info manuals are often examples of documentation done well, and the tar manual looks pretty decent. For example it has sections like "Some Definitions" and "What 'tar' Does", then a tutorial, followed by the formal documentation. It looks like it also separates the coverage of what the program does from the description of how to request those things on the command line. That's also often a sign of high quality documentation.