The LV shooter fired 1100 rounds, with 480 hits (58 Killed, 422 wounded) for a 43.6% hit rate,
This is impressively low, given the target and distance.
Indeed, the casualties caused by LV shooter were -limited- by the fact he used a number of AR15s with bump stocks - he could have easily killed and wounded significantly more people with a different choice of weapon.
Now, no one knows for sure why this guy did what he did, and what he did made no sense at all - but it is clear, he deliberately chose to buy and use AR15s in lieu of other more effective weapons - weapons he certainly knew about and had access to.
The question: Why?
We'll never know, of course.
But, given what could have happened, we should be thankful he chose his weapons poorly.