People who hire developers wouldn't be as focused on the candidates' experience with the technology in the job ad if developers were typically more open for new tech that would be learnt at the job. Try to teach a 40+ Perl developer a new language if you want to see what I mean...
When you compare IT with other industries like the author did, this is what makes hiring so different. Other industries are fine with hiring graduates with no specific experience and the candidates are eager to learn on the job. Whereas in IT, half the people will tell you "can't do this", "don't like that", "won't learn Java" ...