I honestly don't have any idea why but Facebook is a whole lot easier and faster to get your website ranked high in the top search engines. For a regular website, it would take quite some time to get indexed and ranked, depending on your backlinks, content, quality and niche. But using Facebook as your platform can not only bring tons of visitors to your website but help your website get ranked.
If you have a lot of likes and followers, your Facebook page will show up in the search engines for the keywords you are using to optimize it. Since everyone is on Facebook these days, more than likely they will click on a Facebook page that has a product or a service they are looking for by using certain keywords to search it. In the world of internet marketing, especially SEO, there is so much competition. Create a Facebook fan page for your product, gain a lot of likes and followers and your page will be on the first page of the search engines. More than likely you'll be the only one on the first page with a Facebook page and people will click on it rather than any website.