There are still many reasons to why websites can rank high on Google without optimizing. Besides, click-through rate, age, and backlink, the next reason is cross-linking. When your site doesn’t have the best SEO on page and lots of backlinks, your site can still rank well on Google from an overall site perspective if you cross-link on your pages. This is an important part and not just from perspective of navigational or breadcrumb, but from an in-content perspective. When you add in-content link throughout your site and cross-link your pages, in the end you’ll find that all of your website pages will gaining increase in rankings.