RinconVTR,
Despite your supposed "extensive knowledge" because you have owned one, you evidently do not really know how they work. Your second sentence is completely wrong, as are most of the other statements you have made.
The amount of friction between the head and spring bar sockets is extremely high when the WD bars are put under tension. What do you think happens when you lift up on those bars?
That is is where most of the sway control comes from - the friction between those sway bar sockets and the under surface of the hitch head. There is MUCH more pressure on those surfaces than at the L bracket/WD bar junction. Here is a quote directly from the Equal-i-zer web page on how the hitch works.
"Second, the forward and back friction of the hitch arm on the bracket serves as a secondary sway control system." If you or anybody else would like to read the whole page it is located
here. As far as your statement that the friction of the Equal-i-zer hitch head and the normal trunnion or even the round bar being about equal, that is ludicrous! I don't see how you could "easily prove" your statements with "hands on" comparisons when you cannot possibly move the WD bars when they are loaded under tension from a trailer connected to a truck. The pressure of the weight of the tongue and truck pushing down and the WD bar sockets trying to lift up produces a lot more friction than you could ever hope to move - if you could figure out a way to get it done.
There have been numerous discussions on this subject and I think it would be good if you would check out some of them
here and also in some of the links given in that thread.
By the way, I have done a whole lot more than "read on the internet" and have been dealing with hitches and towing issues for over 45 years.
Barney