As email is the original federated system, it might be worth looking to our history to see our future: what was once a utopia for nice people communicating with each other has become a spam-filled arms race dominated by only a few domains.
Email originally wasn’t built with safety and protection in mind, and now we’re racing to catch up - maybe we can do better on the Fediverse, but it’ll take more than just kbin (or even kbin and Lemmy) - this would require coordination between everyone implementing ActivityPub.
(This is also a fun video in general which goes into the inner workings of email.)