re my earlier post.....
I used to do a fair bit of hunting & off roading.... dirt roads, mud, goofing around as a 16-20 year old.
With limited slip, both rear wheels will spin if traction is lost.
I've seen 4x4 trucks in mud and in snow with one rear wheel spinning and the opposite corner front wheel spining.... not moving, well not in the desitred direction anyway..... get both rears spinning in the right direction and you can go places.
That's not to say the 4x4 doesn't have a useful place.
I also had a 2WD truck once... a little nissan taht didn't have limited slip.... It was sitting in a dry parking lot and I wasn't moving an inch. Got out and walked around.... my one drive tire was parked on a patch of ice not much bigger that the tire's footprint..... that little guy would spin and spin but wasn't pushing the truck an inch!
BUT in the end.... to the OP..... if he wants a 4x4 truck and it's not a financial burden for you, support him, encourage him to go buy it, and don't ask why. He'll be happy and you'll be happy.
On the other hand, if it's a financial burden, he shouldn't be shopping trucks anyway.... just my opinion.