Some vehicle manufacturers specify that a WDH must be used to tow up to the max tow capacity of the vehicle. My BT50 can tow up to 2000kg with std hitch and 3000kg using a Weight distribution hitch. So when I tow my boat with the Mazda I always use the WDH, but when I tow it with my Patrol I use the standard hitch. I would use the WDH on the Patrol but the tongue size is different between the two vehicles.
Ron