As per the article, they definitely did call the police beforehand. Clearly the police had taken little, if any, action. It's hidden, but it's there: "my sister had already had a couple of police visits about the previous incidents".
What did they do besides doxing him and confronting him online that helped? None of their 'let's catch him' antics were helpful and were actually stupid.
The confession was online, and they already had the vehicle ID (written down initially and then confirmed on camera). Don't be patronizing please. Hiding out in the car did nothing that they couldn't have done with cameras, without risking violent confrontation and a high speed chase.
You asked "What did they do besides doxing him and confronting him online that helped?"
> The confession was online
The confession was made possible via their "antics", because he knew he'd been caught. Without the experience of being cornered and having to escape, he'd have likely ignored the message as a fishing expedition.
