You're assigning a connotation to the word that I don't really agree with. There's nothing wrong with being a lurker.
There's encouragement to not be a lurker in the fediverse simply because engagement drives adoption and traffic, but I think the goal is ultimately to attract more lurkers
This makes absolutely no sense. The smaller the community is, the easier it is to migrate. They could just go to literally any other service.
The community is the people, not the platform.