You’re joking right?

What you are describing is basically Mastodon

No. Mastodon and twitter are short message services. Lemmy and reddit are content aggregators.

The moment you aggregate communities across instances you remove the ability to moderate them. Because maybe a hexbear mod wants to remove all mention of the Uyghur people, an ml mod wants to remove all mention of genocide against them, and a zip mod wants to remove all the comments about why genocide is good in a thread about god damned Bluey. Do they all get to delete everything across every instance? Do you start having different views of the same community depending on your home instance?

Instance A also cannot moderate the content of Instance B. Your argument is therefore invalid. The point of federation is that instances can agree on a common set of rules and values or not. In that case they defederate from each other. However, this doesn’t work in practice as communities are centralized. Obviously, most of us agree that lemmy.ml is a problem but we don’t federate just because they ‘own’ the instance.

What I mean is that a subset of all Linux communities agrees on a common set of rules and forms a community of communities. Content of all communities is shared with everyone who subscribes to one of the communities. Every community moderates its own content. If one community decides to have stricter rules than the others it can defederate. Basically just like on the level of instances.

What stops us to just defederate from lemmy.ml is that the community is hosted there and all members are linked to that one point of failure.

The problem with this reasoning is that many of the popular communities are actually on lemmy.ml, and they’re not so easy to replace. I mean, in terms of content and engagement lemmy is already a pretty small place as it is.

I think this is a core problem of lemmy as it is right now. This place is meant to be federated and decentralized. Instead it is heavily centralized as communities lie on one instance. What one needs should be federated communities as well. Like say c/linux@lemmy.world is the same as c/linux@someotherinstance.com. this way one could subscribe to communities on your home instance and if the home instance defederates from one other instance the community can defederate from the community on that instance without completely breaking apart