undefined> What would be better, though? Having a P2P-like system where everything is truly federated? Like… Everyone has all accounts and all content at all times? I don’t know how this would work

I think something mandatory in the server instances that runs a blockchain (not crypto to be clear but that is how it works) IE every instance server is a validator node. When you create an account you do it from an instance, it gets recorded into the blockchain but at that point you have a lemmy account. You can directly log in on any instance as YOU (kind of like how SAML/OAUTH lets you use a google / microsoft / steam account) and use the services. When you post it is signed with your blockchain info. You could get banned on a specific instance and that gets recorded in the block chain. Other instances could chose to look at that info and decide they don't want users that have been banned on multiple other instances or on specific trusted instances. Over time your account essentially becomes more or less trusted but the key think is that your YOU and not bound to one instance.