Rob Pike explained it thusly in a 2013 Google Groups reply:
> Rob 'Commander' Pike
> Apr 2, 2013, 6:50:36 AM
> to rog, John Jeffery, golan...@googlegroups.com
> As the author of the flag package, I can explain. It's loosely based on Google's flag package, although greatly simplified (and I mean greatly). I wanted a single, straightforward syntax for flags, nothing more, nothing less.
> Rob 'Commander' Pike
> Apr 2, 2013, 6:50:36 AM
> to rog, John Jeffery, golan...@googlegroups.com
> As the author of the flag package, I can explain. It's loosely based on Google's flag package, although greatly simplified (and I mean greatly). I wanted a single, straightforward syntax for flags, nothing more, nothing less.
> -rob