I think a lot of it is just for the author's own fun, enjoyment, and amusement. Also, golang is probably their favorite hammer. It's not efficient for me to smoke a brisket myself or make furniture by woodworking, but I enjoy it. Not everything has to have any more purpose than that.

bingo. i'm not trying to claim that everyone should do this in go -- it's just a language that i like to use. by all means, use ruby, or PHP, or Elixir, or whatever else you like!