To support decentralization and spread, should lemmy.world close registration at some point to prevent a performance overload due to too many users? Of course, if registration is disabled, there could be a hint placed somewhere near that from other instances you can interact with content on lemmy.world just like you had registered on it. There could be a link to join-lemmys instance overview.
This is the one of the best takes here. It’s a delicate balance. Performance, cost, and manageability. Fail in any of these, and it doesn’t matter, you’ll either lose access to the site or be unable to manage it.
If staffing or money are insufficient, the site should do what’s necessary for survival, but only just before that threshold is exceeded. Users are important, but self destruction is not an option.