[MayeulC]

You are talking about two different things. Parent was explaining what federation was. Both XMPP and Matrix are federated, just like e-mail.

And I'd say that Matrix is closer to e-mail and XMPP than you seem to assume. Once the database is synchronized, it works pretty much the same way. Only if a missing message is detected in the graph, then a server makes another request for the messages it missed (backfill).

Moreover, Matrix and Git are quite different, since you want to be pedantic. Both the synchronization protocol, and conflict resolution are handled differently (Git does very little, Matrix is more like a CRDT in that respect).