Instead of "simple" it's likely they really mean something more like "elegant". Elegance can resemble simplicity because they are both small or appear easy to understand at first glance. To my mind, elegance also leverages deep principles and idiosyncrasies in its environment.

Iterating "by hand" in Ruby is simple in the way a homemade chair is simple. The second example is elegant because it actually takes advantage of the things that differentiate Ruby from Generic Imperative Language X.