I honestly don’t think Lemmy will function well without a way for identical communities across different instances could subscribe to eachother, allowing a single feed of information. This would stop the instances splitting the userbase.

Early Reddit had a subreddit for everything, but most were dormant. However as soon as you posted on it, enough people had it on their front page that you’d get a response. I think Lemmy feels very similar to how Reddit did 10 years ago, except many of the dead communities are totally dead.