This site is currently struggling to handle the amount of new users. I have already upgraded the server, but it will go down regardless if half of Reddit tries to join.
However Lemmy is federated software, meaning you can interact seamlessly with communities on other instances like beehaw.org or lemmy.one. The documentation explains in more detail how this works. Use the instance list to find one where you can register. Then use the Community Browser to find interesting communities. Paste the community url into the search field to follow it.
You can help other Reddit refugees by inviting them to the same Lemmy instance where you joined. This way we can spread the load across many different servers. And users with similar interests will end up together on the same instances. Others on the same instance can also automatically see posts from all the communities that you follow.
Edit: If you moderate a large subreddit, do not link your users directly to lemmy.ml in your announcements. That way the server will only go down sooner.
I like that, then you’d have servers that can develop a sort of “style” and users could browse other communities from that server if they enjoyed another one.
Ultimately you’re right that having topics fragmented over multiple instances has natural risks, I think this is also something that will have a natural evolution where some will become the largest ones, others will die down and smaller ones will have to offer a more niche specialty to attract users.
Your server will be secondary to which communities you choose to subscribe to, but I’m sure that they’ll still have nice general chats and whatnot that you can participate in.
We already have tools to navigate existing communities and I’m sure it’ll only get better, then you can have a discovery solution for all servers and natural selection will do the rest.