This is more important than just marginalizing Left-wing news sites. It's an indication that the means through which information is received, such as the results of a Google search, are now being more rigorously filtered through a process and algorithm determined by major corporations. Are you sure that you want the results for your news searches and what you see on social media to be filtered by mega-corporations before it reaches you? Do you trust seeing what these corporations want you to see? As said in the article, the companies don't believe it is violating your First Amendment rights when they simply remove what is seen on searches, ads, and such, since those websites will still exist. But, the consequence will be one thing: concentrating ideas and news into a safely managed center that is determined to be acceptable by corporations.