Yeah, exactly. Let's say you're on instance B and I'm on instance C, and we both follow a community on instance A. You comment on a post, it will be stored on your instance B, and sent to instance A. Instance A will share it with my instance C because I follow the community, and it will be mirrored on all 3 instances. If instance A goes down, or doesn't exist anymore, the old post/comments will still be there on instance B and C. If you leave new comments after instance A goes down, they won't make it to my instance C. That's my understanding at least, hope that makes sense!