Any decentralized system that is more efficient if centralized, eventually gets centralized by efficiencies of scale.
Email is federated, but everyone running and managing their own email servers is too costly, so for consumers, it migrated to large sites. Web sites were federated, but everyone being web master for their homepage was too difficult, so we get GeoCities, and Yahoo Clubs, and later, Squarespace and Wix, etc. Then blogs were decentralized, but everyone self hosting and authoring blogs was too much, so then we get Wordpress.com and Tumblr, and Twitter, and FB, etc. (even USENET eventually developed super-large hubs like uunet)
For a federated, decentralized system to work and resist centralization, it has to be the case that running a node is dead simple, cheap, and out-of-sight/out-of-mind. It also can't be the case that hosting on a more powerful cluster, colocated with other nodes, gives you large benefits or cost advantages, otherwise, it'll just get centralized again.
Even cryptocurrencies fail this. They have terrible efficiency, but at least they were supposed to be relatively flat, instead of centralized and hierarchical, but instead, a majority of the hashing power is owned by a few large entities, so in effect, back to large financial players controlling much of the power.
I think one day we'll discover some ways to decentralize things in ways that resist re-centralization, but in the mean time, beliefs that you'll achieve cyber/crypto-anarchy by clever protocol design and the federales won't be able to rubber-hose-cryptanalyze you, is a dangerous belief that diverts us away from demanding the government and society agree to the goals of freedom. If everyone wants unfreedom, underground internet usage is a slim consolation.