A turning point in SEO was the Hummingbird update on Google algorithms, in 2013, which made it possible to identify the intent behind the search query based on semantics. From that point on, the focus switched from individual keywords to the relations between them and the meaning they build. In other words, with this upgrade, Google was just taking its first significant steps in using natural language processing to understand the query's context and better sort the results.
The trend intensified two years later, in 2015, when voice search was launched. Today, voice search counts for 20% of the total searches made on mobile.