You don't get to redefine 'federation' because you prefer an approach different than IRC undertakes. It's very much federated and always has been. Data transfer is in the RFC:
2.3 Messages
Servers and clients send eachother messages which may or may not
generate a reply.
IRC has the ability to form networks of servers which share identities and chat channels. There used to be a few large networks and many popular servers were part of one of them. Back in the 90s "being on IRC" commonly meant having a nickname on one of these networks.
Also, where is this federated IRC you speak of? There's no cross-server identity or data transfer baked into the protocol.