Can you obey every rule of search engine optimization for writing content and organizing your site but still wind up not reaching your audience? Yes. It can all come down to whether or not you are using the right keywords. How do you know if the content on your website contains the right keywords? How do you know if they are the keywords that your customers are searching for? How can you know for certain?
You risk a lot by just guessing at the keywords that your customers are searching for.