It seems that someone can create a new sockpuppet account, and everyone in the ring can vote up the sockpuppet. This would probably be a lot harder to detect.

Maybe if there was a 24hr waiting period before a new account can submit articles or comment, it might curtail this, somewhat.

Not really, it's just a case of measuring correlations of voting habits. Plus new accounts with no comment history submitting stories is a spammer red flag anyway.