In the modern days of the web, there are too many information for any single being to consume.
With tons to show for the many queries people have, search engines need to be more relevant. They need to include many other 'signals', making search engine optimization (SEO) for websites more and more complex.
In other words, trends and the strategies to compete made SEO overcomplicated.
For example. SEO strategies can include optimizing the length of the title, the length of the page, the number of targeted keywords, targeting certain verticals and so forth.