Seems to me that these massive handguns have their place. Not limited to but very useful as a defensive weapon against large carnivores or other very dangerous animals that you aren't necessarily hunting, but rather run across unexpectedly while going about your business in the outdoors.
More than a few Africans have been eaten alive by predators that they came upon unexpectedly, as well as hunters who found themselves too lightly armed for massive animals when hunting lighter game. Same has happed in the USA in bear country.
At one time a British firm marketed a cut down No.4 Enfield with pistol grip and 14 inch barrel, built on unissued receivers to skirt the cutdown rifle stigma.
One use planned for these was to be clipped to the door panels of tourist vans used at the open air big game preserves and zoos. The drivers could use these to protect their charges should need arise.
The piece was unweildy for a handgun, but far easier to deploy than a carbine while inside or when exiting a vehicle.
A long barreled massive framed revolver clipped to a pack frame or in a torso carried holster of some sort could be very useful for sport fishermen in bear country.
It would increase the range at which rounds fired in defense would take effect, increasing probability of surviving an attack.
The Canadian government once pursued a contract for a compact all weather bolt action in .308 with folding stock, intended for defensive use by crews servicing communication towers in polar bear country.
While Canada is unlikely to authorise a handgun for use by civilian workers, the massive revolvers in ultra powerful chamberings might serve a similar purpose, and be far easier to pack while climbing towers, or any other type of climbing for that matter.