The federation helps mitigate the issue of too small community since you can interact with lemmy even when you're not on lemmy itself. Found this post via friendica for example(though I do directly post on lemmy itself)
darth_tiktaalik
joined 2 years ago
@TimothyMcFuck friendca federates with pretty much everything including lemmy. As seen with this self demonstrating reply from the nerdica instance.