The key point of the article is that most social P2P systems (Mastodon, Dat) are fully public and do not hide the user's data from the system administrator or physical infrastructure network.
This is at odds with how these systems are often "marketed" as tools for fighting against The Government" or "The Corporations"-- when the open nature and lack of anonymization mechanisms of these tools expose those who are currently technically breaking the law (to prove a moral point) to be trivially detected by law-enforcement.
I personally have considered running a few P2P nodes for fun, but the amount of moderating and administration I would need to do and the risk of the service being used for illegal purposes pushes me firmly in the camp of watching from a distance.