I would say it’s slightly more than this: The vast majority of Lemmy is comprised of only a few things—politics, tech, memes—and it’s hard to find discussions or opinions about almost everything else. The main value of reddit to me is (was?) that you could find a lot of input from people involved in a wide variety of fields, from niche hobbies to more generic areas of interest like history, philosophy, or medicine.

I’ve actually found that there are people on Lemmy with similar levels of expertise, and they’re willing to share it just as well, but they have fewer opportunities to do so, because very few threads get posted outside the 3 main topics. Several times I’ve come across useful and interesting insight, but it was in the comments of posts only vaguely related, so it would have been difficult to find intentionally if I hadn’t run into it.

So, perhaps, this is what could improve Lemmy: starting more discussions about different topics. Perhaps this will attract more people to read them, which might attract more people to post.