But, there are? I can host a repo on GitHub, Codeberg and self host it too. Then I need to watch over main to keep it consistent between those. After that's established, I can do updates from wherever. Link'em in the README.
There are distributed forges? Yes, git is distributed, but often everything around it isn't. The case parent is trying to make, is that the rest ("federated forges") should also be distributed, not just git.
> what is the missing killer feature that needs federation?
Issues, pull requests, collaboration/permissions/access, "staring"/"favoriting", etc.
I think ultimately the goal is that people can run their own forges, yet still collaborate on repositories hosted in other forges, leveraging your existing authentication so you no longer need to sign up individually for each forge.