No idea why/how this system was used.
There are some advantages. I guess it takes advantage of the hydraulic system used for steering. The system is variable speed based on engine temp, which may be more efficient.
There are some systems that use the electronic controller but it also has it's problems. I've seen multiple postings of people having problems with this. Source Engineering has actually come up with a conversion that uses the thermo wax valve.
I did have to replace mine but after I installed the new one I took the old one apart and found a piece of cloth/thread in it. I had my coach into Cummins Crosspoint for a radiator change and they probably wrapped the thermo valve in a rag and a small piece got in it. I was hesitant to take it apart before I got a new as the coach would have been completely disabled while I procured a new part.
2002 Monaco Windsor 38 PKD
2005 Jeep Grand Cherokee w/5.7 Hemi