Their business is to perform the functions the System handles so poorly. Headhunters have developed methods that work because they must. If headhunters don't win job offers for their candidates, headhunters don't eat. It's as simple as that. Headhunters work outside the System.
Headhunters have no reason to make a lot of noise about what they do.
Because their methods work, corporations retain them every day. The bad news is, you can't hire a headhunter. Headhunters work for corporate clients. The good news is, you don't really need a headhunter. Most Americans incorrectly assume there is no option but the System.