The article talks about launching independent servers completely reliant on Bluesky PBLLC so that users may migrate away if Bluesky is ever threatened with enshittification.
Problem is that running independent AT Protocol server is more costly than running an ActivityPub server.
Bluesky is more popular than Mastodon, but there is still only the official Bluesky server. Meanwhile thereās hundreds and maybe thousands of federated ActivityPub servers.