Indeed. Gerber went even further and says that it may be counterproductive to own a business that matches your technical expertise. That's because of the temptation to jump in and do the technical work... instead of focusing on the strategic aspects of owning the biz.

beat me to it :) E-Myth is totally worth it for freelancers to read, and probably startups too. (I'm the former, not the latter, so I don't know)