Adam Kalsey:

"When I look at that job description, I can’t decipher what they really want. What’s the real need behind that job? Do they want a developer, a designer, a manager, or an analyst? They are discouraging people from applying because they don’t have all those skills. A great manager with lots of experience in leading Web teams might not apply because they don't know Photoshop. A hot designer that doesn't have expert knowledge in four different programming languages will send their resume elsewhere."

I've tried to explain this a couple of times to customers who were looking to hire the proverbial "webmaster." Master of what? The problem is, if you don't really grasp how a web site works from end to end, you're not likely to understand how tasks and skills are usually spread among team members either.