You're describing the FBI or your state level equivalent. And they actually do exactly what you are describing, but in measured efforts. I've even had them come by my place of employment before. They clearly lack the resources to work at this scale though.

The problem with a phone number you suggest is that it will get spammed and abused with fraudulent imposters too (the complete and utter destruction of trust in phone calls and text messages should also be corrected by the government, but that's a different topic).

https://www.fbi.gov/investigate/cyber