There are plenty of so called "internet marketing gurus" (the Frank Kern's and Mike Filsaime's) who teach it but most of them are no good. They have only ever sold internet marketing informational products to other aspiring internet marketers. If a potential hire has only sold internet marketing products this is an immediate 'no hire'.
Good luck finding this person!
That's really just a false statement, in my opinion. That's like stating why would any good programmer ever work for anyone else?
Honestly, there are a ton of reasons.
For example, a programmer may wish to work at Facebook so their code is put in front of 500 million users. If they hack something on their own, that's likely not going to be the case.
If a marketer wants to test his/her conversion theories against a large volume of traffic, they either need to spend LARGE amounts of their own money for paid traffic, or build up a large audience of their own. Again, an unlikely scenario.
Whether you're a marketer, or a programmer, or whatever else, working at a company/startup can provide you with opportunities that do not exist on your own.
Those are some of the prime reasons people work for others, no matter their trade...
The people who are good at driving traffic are driven, entrepreneurial, and have the hacker mindset. Of course they would prefer working for themselves without an upper bound on their earning potential.
The fact is that, if you're good at driving traffic, there are still tremendous opportunities for you out there, and you can earn much, much more than any salary could pay.
I actually emailed you with some advice about hiring someone like this based on my experience in the industry, I'll repost it here:
Ranking experience by preference, I would most prefer a candidate with affiliate marketing experience, next someone who managed SEM/media buys for a large performance advertiser, and finally someone with agency experience. Stay away from people who have only done branding, they will eat your money. Also, I know you're looking for a hacker, but I think the most important factor in running internet marketing campaigns is knowing how to sell. Identifying your target market and what their pain points, wants, and desires are is paramount. Optimizing, split testing, etc is important but secondary compared to marketing fundamentals. Finally, watch out for "social media experts". Value applicants based on how many conversions they can bring, and how much they can spend effectively, not on how much they can engage in conversations. Until you can pay your vendors in Twitter followers, all that matters is getting quality traffic and sales.
I think the fundamental issue is that you're framing this as a job for hackers. For whatever reason, most hackers have a distaste for marketing, and would probably be loath to apply for a marketing-type job. They would rather be building things and not worrying about things like positioning or segmentation.