I have only met three DMOZ editors in real life (many more online).
One was a high school teacher that edits as part of a class project.
One was a university academic who edited in his area of expertise.
One was a physician who edited in their area of speciality.
NONE of these were webmasters (though I assume the school, university and hospital did have websites).
Interestingly 2 of them did not even know what SEO stood for!