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.
I do think there should be a hard limit to the number of total users in an instance. Otherwise as you said the content will get centralised in a specific instance. But that limit should be much higher than what lemmy.world now has. Also closing new registration at this time would be detrimental to the overall ecosystem. This is just my personal opinion.
Having the user count far exceed what the servers can handle is also detrimental to the ecosystem.
People aren’t patient. And the current instability we’re seeing will just make people give up on Lemmy after a brief attempt to settle in.
You raise a valid point. But finding new communities is much harder in smaller instances. So there is a chance the user will not find content they are interested in.