Your summary of this phenomenon resonates with my experiences navigating the internet all these years. I find reddit to be the most perfect example of watching something authentic, human, and real... devolve into a manufactured, astroturfed facsimile of a forum community.
Years ago, reddit was filled with interesting discussions and analysis. Beautiful debates would rage on /r/news about current events, with equal showing of opposing viewpoints. Deep discussions on cinema in /r/movies. Excited chatter about the next video game and people's past favorites in /r/games. It was a place to talk shop for any interest.
Today, reddit is a vastly different place. /r/news is a perfect example of how ad companies and political groups pulled it off. Around the height of Trumps office, the left was able to strongly rally around hatred for the man and therefore hatred for any conservative. During this time of high emotion, the /r/news subreddit had a mod overhaul which completely aligned the political framing to 100% progressive, with a search and destroy mentality to all right wing thought. Only certain "power users" with ties to established media companies and left wing political groups would post articles there and any competing user or troublesome commenter would be banned. After only a few months of this, anyone with a centrist or right wing opinion was banned or just left, and today /r/news is now a perfect echo chamber for progressive politics. If a newbie were to go visit /r/news on reddit today they would have to believe that surely everyone must think this way, and surely /r/news is a reflection of reality, but it is not, it is a curated and controlled echo chamber.
The power inherent in falsifying organic communities and engagement in propagandizing and selling things to people is incredible. Our society is increasingly distrusting of traditional media, news, talking heads and the like, and have turned to the authenticity of social media strangers to get a better idea of the real discourse around current events. When those pools of discussion get poisoned, manipulated, and falsified, it further breaks down our ability to understand each other or feel connected.
On the advertising front,/r/movies and /r/television are merely a constant stream of Movie/TV ads and celebrity gossip. /r/games might as well be the front page of a games industry magazine. The organic discussions are few and far between, and the marketing pushes from content creators are ever more apparent. You will see movies get odd posts by some rabid fan who just saw the newest release and can't wait to share how wonderful it was! Several comments agree that this new movie is a joy, great fun! Then you watch it and it's awful, true garbage, and if you search around you'll find out most real people agree... and you realize you were tricked, no human ever liked this dull film, some social media intern wrote that reddit post and paid for flair to pop it up. You start to realize that from mainstream reviews... to reddit posts.. everything online is bought and paid for. What can you believe?
This is the reality of the modern online social media space. Users are cattle to be herded towards products and worldviews and mindsets. Governments and companies alike prod and seduce us towards their desired result, and we're meant to believe that everything we're experiencing is authentic... but it isn't.
The question now is... what's next? We know that people feel more alone and disconnected than ever before, and that authenticity seems to be in dwindling supply... how can we take back the internet? How can real discussion and community build up again? Maybe it's discord, maybe it's web3.0. Who can say... but we cannot accept that this beautiful cyberspace of human knowledge is becoming the worlds largest marketing ploy.