I don't get it: Why would general purpose classifieds publishers (craigslist and ebay) be interested in sharing their revenues with some middle man like edgeio?

I don't get it: Why would general purpose classifieds publishers (craigslist and ebay) be interested in sharing their revenues with some middle man like edgeio? I don't get their aggregation proposal: there is nothing to aggregate - those two control most of the market, plus your friendly local dying Sunday newspaper.