You make a good point. To be effective, vigilantes must first make sure they have the right person, and second direct their activities toward that person in a manner that neither endangers nor punishes innocents.
Sometimes the definition of an 'innocent party' gets bent a bit to exclude anyone who is related to, or had an inkling of, the activities of the guilty.
Did the rest of the people in the house defend the perpetrator? Are they relatives? We do not know the complete story here.
As a rule, few are level headed enough to keep the situation from degenerating into mob violence.
The old adage I posted comes from the days of blood feuds in the Appalachians, when the parties were well known to one another, and the retaliatory acts at least were confined to members of opposing clans, for the most part. A solid patriarchical society kept things in check to a large degree.
Exactly, and that's why vigilantism will never work. Despite what a lot of freepers here seem to think, vigilantism is born in the heat of the moment, and as I said earlier, that's just fertile soil for all manner of evil.