By creating sockpuppet accounts, you can fake more activity in discussions. This encourages real users to participate. Repeat until there are enough real users to sustain a community without sockpuppets.
Reddit did this, as they said in this interview. Others confirm the approach.
Yeah, I agree with the others. I think the instances and communities need to grow organically; otherwise there will always be a kind of hollow feel to the posts.
Maybe when chapo.chat manages to get integration up and running, we could have more interactions (their instance seems pretty active).