I've seen that
I new some dog deer guys in AR and they used #4 also. Their target was the head and neck, and ranges were typically short as the deer bounced across pine plantation roads. They had a lot of hunters and stood off a lot of territory and long established crossings.
Dogging deer is still legal here in my home county in AL. The dog hunters typically use semi rifles. Buckshot is not that common anymore, but dog hunting is on its way out also. Not so in the southern half of the state as I understand it.
The big thing is range. Buckshot of any size is a pretty short range proposition. When a shooter bounds by outside of 50 yds, most folks just can't resist. Thus, rifles.