It's about being honest in reporting. People involved in selling heroin on the corner getting shot is fundamentally different than people in a church/school/bar/mall getting shot.

It would be like calling every car accident involving more than one pedestrian or more than 2 cars, a mass ramming incident. There's not an epidemic of people using cars to kill a bunch of people, but there's enough drunk drivers and people texting to make it look that way if you try.