"Chiefs" of tribes, as well as mods, have tools to refer people to snapzu and get their own invitation codes as well. While this might discourage some of the spontaneous finders, it does help with targeting a specific audience by the Chief and the mods.

Right now, the invitation system is to stop snapzu from getting inundated by reddit users. Snapzu is a bit different than reddit and the admins are trying to keep it a bit more high-brow. Even if they do lose out on some member joining, the slow growth that it allows will help with maintaining the "culture" of the site and not let it get swallowed up by massive immigrations from reddit.