It's called, "Work smarter, not harder."
Perfectly normal to lift take some weight off the rear of the truck to make hooking up the WD chains/bars/whatever easier.
Electric jacks usually have 3500lb rated capacity or more. Your typical 1/2 ton pickup weighs in at around 2200-2500lb on the rear axle, and you give yourself a bit of mechanical advantage jacking at the hitch ball. Trailer tongues are anywhere from 800-1200lbs. An electric jack could easily lift the rear of a typical combination right off the ground!
Not a good idea if you're not on the level, though.