Um not lucky, I just buy appropriately rated gear. I believe without googling the numbers that hitch pins generaly have over a 10,000 lb sheer rating, and I definitely know grade 8 bolts of similar sizes blow that out of the water if you want to be extra safe. As for my hitch tray that my winch sits on, it's rated for 12,000 lbs on a straight line pull. So the weakest point on my setup is the curt hitch at 9,000 lbs.They do make them but your only rated for what the hitch and pin is.So if you have a 8000lbs winch your safety rating using the hitch mount is only 5000lbs and not enough to safely extract a stuck KJ.
And yes I have seen them fail big time so you are just lucky so far
I can't vouch for your buddy's equipment, and obviously anything can always happen, but the right hitch setup for a winch is plenty capable of safely unsticking a gas KJ.