Marv all these times we talked about towing and saying unsafe, I thought you ment with a weight dist. hitch....sorry about misunderstanding that part
I can see no reason other then cost to not use one .
Take the pig gig , i did not see one set up that way . Straight ball hitch , or 5th wheel set ups .
Your point on dually trucks is very true . There stability is remarkable compared to single wheel trucks . No sway out of the rear at all .