The article is very specifically geared towards producing a prototype quickly, not producing a great design. Therefore, similar looking sites don't really factor into the issue being addressed.

You might also enjoy: https://github.com/mbriggs/zurb-awesome-buttons [demo: http://www.zurb.com/blog_uploads/0000/0617/buttons-03.html] - can be installed using bundler and is cleaner than the button gem.