One example - they mine people's labour of searching beyond the first page of results - so when a small % of people really dig into results, they can infer whic

One example - they mine people's labour of searching beyond the first page of results - so when a small % of people really dig into results, they can infer which the good sites are deeper in (e.g. by when you settle on one). Bing doesn't have enough traffic to do this as well, so is less good at finding quality new sites, reducing overall quality. Source: Doing SEO, but about 8 years ago now, the ecosystem will have changed.