https://www.washingtonpost.com/lifestyle/style/facebooks-role-in-trumps-win-is-clear-no-matter-what-mark-zuckerberg-says/2017/09/07/b5006c1c-93c7-11e7-89fa-bb822a46da5b_story.html?outputType=comment&utm_term=.494962d5b4e1
This article may focus on the election of Trump, but it's a sign of the bigger picture. Extremism has arisen in this country because of propaganda spewed from what was once a quiet minority. That minority has been able to grow under the use of fake or skewed news stories shared rapidly on social media (Facebook). Facebook has led to the birth of alt left and alt right "news" organizations that are actually making it difficult to dessiminate between real news and stuff thats made up. While you may still get your news from multiple sources, it's now found at one place, which also happens to either suggests stories to read, OR allows you to see stories friends (many with similar viewpoints) have shared.
If Zuckerburg runs for president. May God help us. It will be worse than Trump by a lot.