Self-policing is problematic because it's unwritten law. Newbies can get penalized for doing things that they don't necessarily know are wrong, and that seem to be legitimate and OK.

It's ridiculous to expect every new user to learn an unwritten set of rules that are enforced by various community whales and their bots.

While most automated down-voting is targeting larger accounts and is done with good intention, the better approach would be to set up community guidelines for what actions are and are not appropriate, and modify the code where possible to prevent inappropriate actions from taking place to begin with.