Instance owners ought to clean up all the unused communities that were created during the Reddit exodus by inactive users/mods only wanting to hoard the names. They're basically redirecting traffic from actual communities and into a void.
I wonder how often it happens that some user has a hobby/interest, and go search for a community for this interest. They'll find an empty community and leave without posting.
My theory is that if the dead communities didn't exist, people who actually care about the topic would create their own active communities.
When you search for a community in lemmy, by default, the results are ordered by subscribers. If there is an active community on the topic, it will appear above any of the others, so the only way people are finding empty communities is if all of the communities are empty