Centralization makes it harder to deal with bad actors, because the cost of moderating a huge platform is massive, and the centralized social media platforms we have today have been unable or unwilling to do it.

Federal platforms like Reddit and Discord are able to moderate effectively, on the other hand, because the cost of moderation is devolved to the municipal governments: subreddits and servers. Moderation at this scale works; it works right now on this forum.