But a quick death prevents both. Having several neat, .22 or .30 cal holes punched through you OTOH, IS needless pain, harm, & suffering.
Don't some of "them" also bitch about the use of .50BMG against a person with a rifle on this same ground; or, at least on grounds of "disproportionate" force?
It's the enemy, stupid; kill them quick and in overwhelming numbers, by any means at hand, until they all die or quit.
That's why .50 BMG is designated as an "anti-materiel" or "anti-vehicle" caliber, as are the rifles that fire it.