This is an over-rated post telling us about a problem that only exists in the ignorant. 
  It's cut from the same cloth as all the misinformed "Twitter's Dropping Rails!" posts 
  and I'd expect better from the voters on HN.

Cross Platform Software Distribution is a challenge for any language/technology. I guess the upvotes for this submission do not imply readers here agree with the viewpoint on Ruby given in the article, but rather think it is an interesting topic worth discussing. (I might be completely wrong in this assumption)

I am an active user of Ruby, and agree with you that the author is making over generalized sweeping statements such as: "yet it's the standard, recommended practice in the Rails community, because it makes it easy to "guarantee" behaviour in a given environment"

There is no silver bullet for software distribution in any particular language. One has to be smart and pragmatic enough to weigh in the pros and cons of static linking/vendoring in their particular case, and then take a wise decision on it.