So if I'm comprehending you, you are aware social media is addictive, but are not aware how. 4chan addiction is simple, it has niches and content you don't find in normal society. You go to it to seek content that otherwise would not exist in your day to day life. But most of humanity doesn't need it. You can't buy food with it, find shelter, get a degree, etc..
Real social media makes community outreach easier. Instead of going to a community center, library, or bar, you can post on a social website “Hey, we like anime, come hangout!” and build friendships from those legit social interactions.
What makes the other ones _addictive_ is all the Skinner games they embed in their design:
https://hai.stanford.edu/news/psychiatrists-perspective-social-media-algorithms-and-mental-healt
https://scopeblog.stanford.edu/2021/10/29/addictive-potential-of-social-media-explained/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6679162/
https://hbr.org/2022/11/our-social-media-addiction
likes, reposts, gamifying, those things content addictive. It's gambling, but more tuned to your desires, instead of just money.
Like I said in >>2, they already exist, but just like mice, people don't want to use anti dark pattern technologies, they prefer the Brave New World (Aldous Huxley 1932).