Everyone is in complete agreement with this statement. It's also not the point. The author was observing/positing a greater degree of version inter-dependency in Ruby gems, not that Ruby gems are inter-dependent and Python packages aren't.

Nor is the discussion regarding the languages only. It is about the additional set of tools that one uses in order to build a web application in those respective language. Consider the phrases "and its associated frameworks" and "similarities between Rails and Django given the structural similarities between Ruby and Python" as clues that this is not about the languages per se. Or from the previously written essay, "the construction of a Ruby on Rails app ... that makes use of Devise for user authentication, RSpec for unit testing and Cucumber for behavior testing."

The author therefore quite clearly "recognize[s] the parallel between installing several gems and installing several packages" and is instead focusing on a specific aspect of that parallelism; inter-depenency.