The best place to buy books online has recently acquired the best place to review books online. But was it necessary for Amazon (AMZN -2.56%) to acquire Goodreads?

Founded several years ago, Goodreads has built out a social media company for people to discover and share books. In doing so, the start-up has amassed a growing number of quality-driven reviews, which seemed to threaten Amazon's core competency when it comes to e-commerce book sales. And that would be a huge blow to the e-commerce website. 

How big? Currently, Forrester Research estimates that the e-book market may grow to $13.6 billion by 2017 -- and that's just in the U.S.

Fool contributor Kevin Chen thinks that's only half of the story. While Goodreads could have taken on Amazon, it could have also done so as part of Amazon's competitors: Apple (AAPL -1.22%) or Google (GOOGL -1.23%). Both companies have not only entered the e-book market, but they have also tried to build out their own social platforms in the past -- with mixed results. So, it's very possible that they could have acquired Goodreads. And in that case, Amazon would be in a far worse position today.

To learn more about Goodreads and why Amazon needed to make this acquisition, click on the video below.