If by cheapest you mean, a good cog for a good price, then yes, that is exactly what an employer wants. At the end of the day, everyone likes to feel like a winner.

While it would be nice for everyone to be great and welcoming from the outset, it isn't realistic to have that expectation. If we inspect the job ads out there, it is pretty obvious that many employers feel that they can get away with a crappy job ad but still get the cog of their needs with it. So this may not be sheer luck - there are probably more good developers than companies with great job descriptions.

But yes, I do agree that a company can increase its chances significantly by tailoring a job description to its intended audience a bit better (but perhaps they already are? ;)).