How many mass shootings do you think required someone to be accurate from more than 50 meters away?

That one guy in Texas back in the day up on top of a tower is the only one that comes to mind. But he was a former marine, so he had training.

Even the Las Vegas guy didn't need to be accurate. He was shooting into a crowd indiscriminately.

Try again, buddy. These school/church/theatre shootings are happening within range of pretty much any gun. (I guess birdshot might not work, but you get my point). Entering a room full of people means you don't need to be accurate more than a few dozen feet. Even an auditorium is not very big/people can't exactly run away from you.