Vince, I’m not sure if you’re picking on the OP’s example or the Pink Cow.
The Pink Cow did have a front winch also. For me, the rear winch was an exercise in ingenuity ( to meet all MY criterias) , creativity and the fun of making it. The main objective was to maintain a trailering ability and capacity, and used primarily to load dead vehicles (or whatever) onto the trailer. As with my other truck at the time, the rear winch is extremely useful.
The resale of the truck was enhanced, as nothing is changed to the truck and I had a 2nd tailcone for the machining, completely bolt-on and reversible. As anyone that has serviced their E brake on a Pinz, not too difficult to remove. My only expense was the folded steel for the tray and my time. 42 lbs is not much weigh really, the front mount weighed in at 20 lbs, and made it in a ½ hour with materials laying around the shop… super easy with a 40t metal muncher, cold saw and a welder.

Tthough it may look complicated and expensive, the rear winch setup probably wouldn't cost much more than what people are paying for a custom bumper w/bullbar and winch.
A front winch mount is almost always easier,dead unused space, takes up no rear storage room and is pulling in the direction you usually want to go. Spooling to the opposite end of the vehicle requires some engineering to avoid vehicle components and the winch mounted so there is no undue stress on the frame and mounting points ( as in the front of the Pinz where a front winch spooled under the truck to the rear will pull the the front extension down).
There are many arguments for where a winch should be, but it always comes down to what you want it for and if for recovery, which way you want to recover yourself, forward or back ( though racing, its almost always forward).
Unimogs have had options for front, middle and rear winches for almost forever. Land Rover 101FC had PTO mid mounted winches that could be spooled either direction ( though rear pull recover couldn’t be done with the use of the wheels). The US FMTVs use a hydraulic mid mounted winch that also can be spooled front or rear.
Oh, btw, as an added thought. The added weight to the rear by the tray may be a lot less, as it replaced most of mass of the cast tailcone.
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The Trojan Horse... the 1st Pinz used to covertly carry troops into battle .
ATL Pinzgauer XM 718K TUM(HD) 6x6 FFR (aka The Green Grail)