Here's where I disagree. You haven't doubled your salary BECAUSE of your policy of not working with recruiters, but rather DESPITE this policy.
Deciding to disregard any recruiter opportunity is just shutting out quite a few things that you probably won't hear about otherwise, especially at the higher levels. Exec roles are often handled by retained recruiting firms and aren't as well publicized as entry level and junior roles. So just saying "I will never work with a third party recruiter" can certainly be your policy, and you may save yourself a fair amount of time by sticking with it, but that policy is doing nothing to advance your position (career, earnings, etc.)
The reasons that there are so many incompetent recruiters are many, but a few are:
- low cost: companies hire entry level recruiters and pay them next to nothing in guaranteed compensation (mostly commission-based). The good ones will make the company a lot of money, and the bad ones can't afford to stay in the industry because they aren't making enough in commission - so they 'go away'.
- low skill: the skills required to be a good recruiter aren't typically taught in school, so they aren't coming out of college with a strong foundation. They need to learn and be successful quickly (because it's commission-based)