Paul Graham wrote about the entanglement of news and PR companies over 20 years ago: https://www.paulgraham.com/submarine.html

It wouldn't surprise me if something similar is happening with social media and indeed a lot of the news is astroturfed to some extent, though I agree we shouldn't discount the extent to which people are willing to participate in this by reposting popular content for a quick ego/karma boost. And increasingly that reposting is done by bots.