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?
Vigilantism is bad because of the slippery slope issue. It starts with solid proof, and then slowly declines towards “vibes”, or fabrication of proof.
“Beyond reasonable doubt” is the high bar set by the legal system, and they have the processes in place to ensure that the bar is met before declaring guilt (its not perfect, but it is so far the best system we have).
If the proof is solid, and the law enforcement is functional, its better to hand it to them and let the system do its job. If the law enforcement isnt functional, vigilantism is all that is left, but you should strive to meet the “beyond reasonable doubt” bar. E.g is the evidence good, do you have the right person, could someone else be framing/manipulating the facts.