I get the point that job spec should help to sell the company, but as far as being specific about problems domain that's less important to me.. I just want someone that's smart and get's things done. There is no specific problem they are hired for but wide net of problems. this may be different at a company that's working in a more narrow field? in my line we usually look for full stack developers with business acumen + hunger and drive. now get me a spec for that!
The example was better ... how? It said general things like "Rails is one tool you use...", "Passionate about..." and "Able to leave your ego at the door...". None of those is a tight job spec for an engineer - in fact except for the Rails reference it could be anybody. Marketing, management, janitor.
I like the part about arming others to help you. I've found this to be critical. The more your job specs reflect the excitement of working at your company, the more other people can evangelize that for you.
I've found describing the kinds of problems you'll solve (not in a salesy way) and what the company actually needs help doing can really engage the minds of potential hires.
I'd actually like to see some examples of over-describing problems to engineers in a salesy way. That could be a fun follow on post.
As a hiring manager definitely fallen into this pattern. Note to self, rewrite my job listings!