What's interesting is there have been more than the usual number of downvotes for this thread. I wonder if using IP info admins can determine if these downvotes are clustering from within an org?
Detecting and preventing brigading needs to be more sophisticated than just looking at IP addresses.
Need to determine if groups of users are acting in concert across multiple posts and comments, regardless of IP.
Should that be prevented? It's not really distinguishable from the scenario you prevented.
Independent actors are far less correlated than centrally orchestrated groups.