I’d even say that this illustrates the success even more…

• lemm.ee shuts down, iirc, because it took too much time and effort to run the instance. Not really a sign of inactivity.
• the platform keeps going! The whole idea of a federated network works, as a single instance going down doesn’t impact other ones. As it happened before, see e.g. feddit.de.

So Lemmy as a whole is alive and healthy - and successful.