I made a similar post about this a few days ago. I’m not sure if you were inspired by that post or if there’s just something in the water. Overall, I believe that activity creates activity in a snowball effect. For small sites like Lemmy or other fedi groups, I think having so many dead, bot-driven communities hurts the overall activity of the group as a whole.
I browse /all/new pretty much exclusively, and I see all the time posts in communities made for specific TV shows, made by the same person every time, getting zero traffic or engagement. The communities themselves usually have only a few subscribers. Just to address the elephant in the room, I think this type of behavior is carried entirely from Reddit refugees who read online and thought that Lemmy was a 1:1 substitution for Reddit, without realizing that the Fediverse’s user base is just a percentage as Reddit’s, and that fractalizing groups into such specific topics out the gate hurts discovery and engagement.