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.
Did something similar happen over there?
Some user there confessed to making sock puppet accounts to fuel discussion. But I think it was in a specific subcommunity rather than a sitewide undertaking.