If all those people visit your site, that's the kind of exposure you want. This is my new pet theory. The Internet is overwhelmingly large. Nobody can take it all in. Nobody has the time or the desire.
Authors hang out over here, dog lovers over there, etc.
We use little pieces of the Internet. If you've been to my site, odds are you're a writer. We have our community as well. All writers visit Inscriptions, all writers visit their publishers' egroups, etc. But let's pretend you sell your book to everyone in your community, which you won't.