A couple of major platforms like Facebook and Twitter, YouTube, have become in many places around the world a de facto public sphere. Especially in countries that have less than free Internet, less than free mass media. And these countries have transitioned from a very controlled public sphere to a commercially-run one like Facebook.
I often try to tell people that Google is not providing information retrieval algorithms, it’s providing advertising algorithms. And that is a very important distinction when we think about what kind of information is available in these corporate-controlled spaces.