Who needs documentation anyway?

I remember a tutorial once, which explained how to install rails like this:

gem install rails -y --no-rdoc --no-ri --include-dependencies.

How, come the user, as a novice, does not need the documentation?

Well, the explanation was simple. If you include the documentation, it will take a long time to complete the installation.

Why do they think, that the new user, which is struggling to learn a topic, does not need documentation?

Seriously, I know documentation can be pretty bad occasionally or even missing, but this is absolutely nonsence, and shows how little people think out of the box.