Some people will go the extra mile, but they are not going to make or break a book's sales. If you are selling books directly yourself, then you also have to make the sales pitch and close the sale. That makes you job harder but not impossible. Finding your audience on the Internet is not the same as making it easy for people to find you. You need to identify resources where you can initiate contact with potential readers.
Resources means Web sites, mailing lists, and news groups.
Approaching your audience is basically advertising. You have to advertise yourself because you need to build up name visibility. You have to advertise your book because people don't have any idea it exists, or that it might be something they want to read. Name visibility is important because it lends your book credibility and gives people a reason to look for your Web site. Informing your audience about your book goes well beyond building a Web site and submitting it to search engines.