No problem - some things need a couple rounds of discussion to get the idea across.
But there's a little more clarification needed:
Originally Posted by Losangeles
...my tug is a Acura MDX and I'm towing a 17' Casita travel trailer. Tongue weight is about 300-ish lbs.
My hitch has a 500 lb tongue weight rating, so by your logic I dont require my Curt 17000 WDH.
The tow vehicle is much more than the hitch; I didn't say some hitches
can't handle the tongue weight, I said some tow vehicles
can't handle it. The hitch weight rating of the MDX may be lower than that of the hitch, but whatever the rating If the MDX can't handle the tongue weight of a Casita 17' well (which doesn't surprise me), then this seems like an example of a combination which needs a weight distribution system.
A tow vehicle with a longer wheelbase would have less need for WD; for instance, my Sienna tows a trailer with about 300 pounds of tongue weight and has no need for WD to do that. If you go more extreme and tow with a Ford F-450, you certainly don't need a WD system to tow any Escape... but of course you can still use one if you want.
For any trailer there's a tow vehicle that can properly handle it, others than can handle it with extra hardware, and many which are just not adequate.