Why should this become a place of witch-hunting?
You give no reason why it should be implemented other than that gaming sites has become more sophisticated.
That is not enough justification, especially since
-) i don't see clear signs for HN degrading in Quality
-) i am sure that pg is concerned about HN and has implemented some measurements to guarantee the high quality of this site for the future
No need for such drastic measurement just yet.
If the data is anonymized and there are no details published that can be used to identify the real user involved, it's no harm no foul. This wouldn't be about witch hunting but simply pattern matching.
We wouldn't be identifying witches but the act of witchery. We would never know who the witches were, only pg would. There would be no elements of shaming or individual people called out. This would be entirely ad hominem free.
Where's the evidence that these rings, if they exist, are having a detrimental enough effect on the frontpage to warrant something like this? Why is it so bad that PG, his fiddly algorithms and his staff of moderators can't deal with it?
Science should be a good enough reason to do it ;)