'Return to centre' steering dampers

Never had one but they sound like a bit of a gimmick to me.
Vehicle manufaturers go to a lot of trouble to design steering geometry with good self-centring characteristics. All one of these spring-loaded dampers would seem to do, to me, is (a) put extra stress on the steering box and linkages, as they have to compress one of the springs every time you turn the wheel and (b) partially defeat the damper itself - the damper has to now resist the spring force as well as any 'natural' kick-back forces.
I'll stand corrected if anyone has some good scientific reasoning but they don't seem to be a very logical device to me. Maybe for heavily modified competition mackines?...

Yo, good thing

I had a pull to the left in my GU Patrol, from new.
Nissan said it was within Spec.
Fitted a one dgree castor kit.
heaps better, still pulled a bit.
Fitted a return to centre ------>> problem gone

Been a while (5 years) since I bought it. Think I paid about $150.

Brand is Tough Dog. It has an external spring mechanism & I understand it is the only one available in that configuration.

Took about 20 mins to fit at home.

Cheers

Front end shimmy is most likely caused by insufficient castor angle and a return to centre damper may only mask the problem.
In Sept I was about to be passed by a near new road service Landcruiser ute near Anakie Qld whilst I was dawdling along & as it pulled out to pass me the most alarming shimmy I have ever seen commenced with the front wheels swinging from side to side by about 10 inches from centre.
Thought something had to break but the driver backed right off till it disappeared
then was later able to pass me at a gentle pace. So much for official road service vehicles, wonder if it was a Toyota dealership?

They look good and steer good but it makes them a bugger to work on the front end when you need to keep the wheels turned full lock whilst jacked up for eg. doing brakes with out disconnecting them.