Travler, I pull with a F150 and use a WDH......1 reason is that it came with it when I bought the TM.
Without the WDH, when I set the TM tongue down on the ball, I loose 220 lbs. on my front axle, and gain 700 lb. on my rear axle.....I still have a margin of 600 lbs. until I reach the GAWR on the rear axle, so everything is within stats, unless I load over 600 lbs of camping gear in the truck. But my concern with this is that the geometry of the truck is off. Ideally, when you load your truck bed, the center of the load should be right in front of your rear axle.....most of the load is going on the rear axle (where the manufacturer intended it to go), plus you are loading the front axle a little also.
The WDH gets this load back on the front axle, puts some on the trailer, and reduces the weight on the rear axle. Some folks on this forum with heavy duty trucks put most of their camping gear weight behind the rear seat, and towards the front of the bed, therefore putting some of that load back on the front axle. That works for them, and might for me. But after tweaking my WDH several ways, I can really tell a difference in how the truck drives. I even use different chain lengths depending on if I have a full tank of water or not.
My F150 came with the factory tow package. The hitch is rated @ 500 lb. weight carrying, and 990 lbs weight distributing. When I weighed my TM, the tongue weight was 480 lbs....including the weight of the WDH which is 65 lbs. Since then, I have added an extra battery to the tongue, topped off the propane tanks (which varies, of course), and usually travel with a full tank of water since I dry camp mostly. I betcha that tongue weight is over 550 lbs now.....over the rated factory hitch weight carrying capacity.
Betcha a lot of F150 owners pull that kind of weight OK all of the time. But for me, I want to get the intended geometry back in the truck while towing, have a comfortable trip, and stay within the stats of my hitch.
Chap