So if I understand this right, you pick a server and your server account can post on that server and any servers that that server federates with.
So what happens to your account if the server you joined goes down? Yes, you could always create a new account somewhere else, but you lose all your followed communities and post and comment histories as well.
In mastodon, you can move your account into another server. Technically it just copies your accounts, disables the old one and instructs all people following you to follow the new one. Here we don’t have the “follow” problem, so less hassle, but not clear what happens to the communities of a shut down instance. Do they stay cached in other lemmies, but unable to post more into them?
I don’t know if there’s a community transfer feature though
There should be a failsafe for this because as this grows, you’d also have a lot of servers which are not feasible to maintain anymore and thus they’d go down. Maybe an instance dedicated to archiving could work. Other instances could refer to that archive in order for users to migrate without losing their settings.