They know how to manipulate you to do/buy stuff you weren't looking for. That's what makes a profit.
It has always been this way (also in tech) because those things are the products of companies (main goal: profit, usually under a sneaky slogan), but it is becoming increasingly invasive. Don't be evil: think different.
It's about minimizing the annoyance for the majority of users who will misspell some popular thing.
Also, I believe that showing actually interesting content is bad for the businesses because it might make the user stop to think and pursue something meaningful instead of continuing to use the product.