Well, that diagram brings up an interesting point. In fediverse if the host dies the federated content can still live on (theoretically, I haven’t checked to see if they cull content from dead hosts) but ATProto would dictate that the host is missing and therefore all content associated with the host is now immediately 404.
That shoddy code rots when you update the compiler. (And occasionally good code, depending on what rules the compiler wants to start enforcing)