Yes and no, they do follow what the hiring manager said, but then the HR personnel usually don't know Jack Squat about what those technologies are that the Hiring Manager wants. So by default they look for a degree. Then when the Hiring Manager says "I want someone with 5 years of experience in the IT marketplace and make sure that they have .NET and Windows 2000 experience." then the brain-dead HR drone screens out people that do not have five years of experience in ".NET" and "Windows 2000" despite them not being out for that long.

Not all HR personnel are like that, thank goodness, some are actually hip to the technology like a local cable company I interviewed for. The HR guy there knew the technologies I would be working with, and didn't screen me out because I didn't have a four year degree or higher.

Also sometimes the hiring manager doesn't know what she/he is looking for. That is how those "10+ years of Java" and other impossible job descriptions get made.