I do think Facebook has a lot of pull. Many people get their news through their Facebook feed (an awful idea) - at least many people that I know. And it's the largest place where you can discuss things with close friends and family in mass. Other places on the internet allow mass broadcast - for information dispersal content not only matters but also source/reputation.
Yes, similar case for Google... Looking at some countries where Google has 90% market share, when you are deleting something from Google, you are effectively mostly deleting the content page itself - at least reducing the discovery by a factor 10, which can be critical.
