It's unfortunate that this comment is buried so deep and that generally this topic is under discussed.
Media has always been a force for controlling popular opinion, but in the age of social media it's going to new extremes. There are forces that try to control how you see the world on all social media platforms and do so to attempt to shape your opinions of the world and modify your actions.
You can visibly see Reddit has been completely taken over by bot, shills, and other controlled accounts. There is no sincere, real human opinion posted on the front page.
Even HN is not immune. "Bad news" has long been forbidden here, and there is a range of topics that, even when heavily upvoted by the community, tend to disappear within minutes.
Large portions of the things posted to the Oakland subreddit get flagged and removed. Almost anything mentioning the city in a negative light gets flagged. Crime reports / trends, anything.
Sarcastically chuckling about the state of the city as a long time resident gets the ban hammer.
Imagine if one company owned all the local news papers and replaced all the content with wire stories and the lowest quality local content or a fox news like company bough local news to run a propaganda operation. Oh wait that's real.
"Imagine if a handful of ultra-billionaires controlled almost all social media in the US." doesn't feel less threatening. The fact that Congress doesn't consider this a problem feels like the bigger problem.
Imagine if Japan owned all the newspapers in the run-up to WWII.
That's not to say China is the only one with propaganda.