The cumulative heat in this age old debate is enough to melt even N.D. snow.
I use 4WD all the time. And at the same time, I never use 4WD.
I leave the front hubs unlocked, and use the gear reduction of the transfer case for to get granny low to save the auto transmission torque converter from heating up during low speed back and forth moving a heavy trailer. Works for up steep driveways too.
Now, I'm helping a friend look for a transfer case and rear drive line for his company service truck that was ordered as a 4x2, to "save money". despite my strongly suggesting that he order a 4x4. Well, 3 full transmission replacements later, he gets it. He didn't save money after all.
We have the same chassis, only difference being I'm still on my original transmission, in part because I have an extra gear box for 4x4 (4-LO) that I use in 4x2. I can back up any trailer I want without fear of overheating the transmission. He will only put his construction trailer in pull through situations, so he doesn't end up buying a 4th transmission.
For a tow vehicle with an automatic transmission, the 4-LO is worth having, as long there are manual hubs to keep the front axle unlocked, or some type of electrical switch override that enables the transfer case to be engaged alone.
If there is any slight penalty in weight or mileage, it has been more than repaid in saving iffy automatic transmissions, and/or weak clutches (or weak quadriceps muscles) in manuals.