I don't really think I need an intro for this. Let's get to the good stuff.
1. No XML Sitemap
XML sitemaps are files that list all URLs that are available on a site. Their purpose is to allow site owners to submit all existing pages on their website to search engines for indexing. Once submitted, XML sitemaps tell search engines where to look to find pages to index. This will help pages on your site become indexed more quickly than they would otherwise.