Was recently reflecting on this excellent piece by @jgoerzen comparing and contrasting p2p/federated/centralized systems: https://changelog.complete.org/archives/10216-the-hidden-drawbacks-of-p2p-and-a-defense-of-signal
The drawbacks for p2p and centralized systems seem to be mostly inherent to the technical requirements necessary for things to function.
The downsides of federation are more practical (who/how deploys and maintains the servers). Good reminder that organizational structures like technical "communes" need more emphasis!