Comment by cucumber3732842

The terminology was specifically to counter the slight of hand you just did.

Over time the definition of "mass shooting" kept getting watered down to include a lot of "normal criminals with normal criminal goals they are trying to further by killing" shootings by people who wanted the number to be bigger to mislead the public into thinking indiscriminately targeted, killing for the sake of killing type shootings perpetrated by people who are mentally ill are much more common than they are in order to push various policies.

So then the people concerned with studying the latter had to come up with a new term that only encompassed people going off the deep end and did not include normal crime hence "active shooting"