Where do you draw the line?

Paedophilia? Extremism from the far right? From the far left? Stealing cars? Stealing bikes?

Report someone to the mods, if you think he or she broke the law. They will hopefully report it to law enforcement authorities.

Report someone to the mods if you think he or she didn’t stick to the rules for this community so they can decide.

Anything else can fast be denunciation, not vigilance. So it’s also kind of protecting yourself to not publish “evidence” of misconduct.