I don't think the authors intention is to compare the relative merits of the languages in the context of a particular project. Its more about horserace and mark

I don't think the authors intention is to compare the relative merits of the languages in the context of a particular project. Its more about horserace and market niche. And these are terms in which startup founders are accustomed to thinking in - in the absence of data, you look at related trends and use your reasoned intuition to think about the spread of new ways of doing things. My guess is that a lot of people read that comment and figured that it made sense and captured conventional wisdom in a succinct way. As an aside, because language adoption has network effects, the fact that a lot of people can get interested and excited about Clojure is itself meaningful, which is why I upvoted it.