Not only is the homepage of your website analyzed. Tool SEO checks all subpages and determines if there are broken links, pages with too little text, if the page speed is too slowly, etc. This is important because search engines with their algorithms simulate the behavior of a user. These erroneous or poorer pages are classifying the page as less good. This leads to a bad ranking on search engines and can be responsible for the fact that you have too little traffic and less customers that visit your site.