Very easy to game, actually it already is gamed in a couple different ways. One method - let's say you have a site about nutrition, you could find a doctor who

Very easy to game, actually it already is gamed in a couple different ways. One method - let's say you have a site about nutrition, you could find a doctor who wants to improve their search rankings (or find an agency that works with doctors to improve their rankings). Ask to put them on your website as the author or editor with a link back to their site. It's a win for both parties and Google can't really detect that since it isn't a two way link scheme.