repo of ruby extensions OR rubygems.org??

just learning ruby on rails and i want to know why we need Index of /repositories/devel:/languages:/ruby:/extensions if “rails new <App_Name>” command automatic download the last gems and the missing gems from rubygems.org?

In this wiki article I wrote, I described setting up Ruby on openSUSE 12.3 and how to download gems for that specifc use
http://en.opensuse.ort/User:Tsu2/Kibana

You’ll note for example that I warn the User that the common “bundle” tool from the openSUSE repository works, and the one from the official Rubygems repository doesn’t.

HTH,
TSU