As a software programmer myself I can say that's a pretty bizarre argument to make. Informally, almost all experts have a tool/language they feel gives them an advantage, and language holy wars are all about this topic. Doesn't mean they aren't just making it up, but worth considering that people saying "Node is better than Rails!" "TDD is better than <anything>!" can't simultaneously claim "There is no way to order different approaches by productivity".

But in fact, they is a way, and such measurement has been happening for long enough for us to develop reasonably accurate models of how it changes over time e.g. due to tools getting better, see Yannis' Law, which I confirmed myself a couple months ago (example task took me about five minutes not including when I read the description, so I'm within a factor of 2 of predictions -- I think we may need a better task in a decade or so, it's rapidly approaching weird task-size-minimums).

http://cgi.di.uoa.gr/~smaragd/law.html