To those of us who are primarily shotgunners, a .410-bore is a mouse load typically relegated to .410-bore clay target events, firearms familiarization for youngsters, and nuisance targets. Like many folks, my good guns are locked away; but, there's the ancestral single-shot 3" .410 in the coat closet and a box of shells in the mantle clock. It's not my HD go-to gun.
On the other hand, to a pistol shooter, a .410-bore shot shell makes a revolver a hand cannon. It's the proliferation of the .410-bore revolvers and "HD" loads specially tailored to them that has folks thinking about the .410-bore as an appropriate HD load.
Is the .410-bore shot shell appropriate for HD, it all depends on your perspective. But, as Dave McC reminded us, "It beats bare hands…"