I suspect the author may not have ever had the task of filling a specific developer position on a project with specific skills. Putting out woolly descriptions like he suggests will flood your inbox with hopefuls, wannabes and chancers. You've then got a mountain of work to get through to filter out all the garbage. I suspect in a flat job market like we have at present, the task would be that much worse.

You might triple the amount of candidates you get for an interview, but chances are you're still going to go with the one that has the best cultural, technical (read:language/environment) and business experience fit for the job. Which can be done by explicitly stating this in the job ad in the first place, saving everyone a lot of bother.

The only reason to frame an ad in less-than-specific terms is if you're looking to fill long-term positions, like graduate jobs, jobs where the whole team will be learning a new technology together or research-like jobs.

Paying employees to learn on the job is not a successful recipe for time-critical projects, no matter how bright the candidates are.