my understanding is the biggest reason to use rope is the safety, when winck cable breaks it goes flying at very high speed, a broken steel cable flying through the air can really mess up your day if you are in the way especially far form medical care with a stuck truck and no winch
the other danger of winching (sudden slack take up) is still there, but that is more predictable
Edit* stolen from
http://www.off-road.com/4x4web/faqs/winches.html
A. Be aware that a broken winch cable can have enough force in its whiplash to
cut through a truck's roof and windshield. Imagine what would happen if the
cable met a person. A cable that hits a small tree will tear the tree down. A
cable that hits a large tree can wrap tightly around a tree so a person behind
the tree is not necessarily safe. Solid objects such as hooks and snatch
blocks will fly through anything, including a truck's hood, if a cable breaks.
People should stand well out of range of the cable and never in line with the
cable. Furthermore, if a cable breaks, the truck being winched may roll
downhill, so never stand downhill of any vehicle being winched.