By exposing, I mean showing them up in a highly public subreddit/community/forum etc with solid proof (direct links showing them grooming someone they knew was underage, archived voice clips, webpages, screenshots etc) and getting that community to instantly turn on them, or in some cases getting them banned from the community because the mods saw the evidence and decided that they don’t feel safe having that person in their community.

Also, is vigilantism generally seen as a good or a bad thing?