I can't comment on the accident, could be any number of reasons, my own experience in winching at high altitude in the snow are these,
I always had a crewmember toss out an orange smoke flare at the point of the winch and if able to determine the wind, another one up wind nearest the ridge line.
Wind travels over smooth snow so quickly, and it can really surprise you if you are not prepared for it.
I always attempted to have an exit path that allowed for a pedal turn with the airframe if it was about to go into a max pitch maximum pedal hover, ie starting to settle, turn away and attempt to add power back to the rotor and fly down the hill. sometimes you couldn't do it, but I always tried to allow for it.
Depth perception is a real problem in snow, and I can really sympathise with any pilot who has ever experienced it.
It sounds like the crew were on the ball if they only winched in one person per trip, especially with the power that a Blackhawk has. I hope they are all going to get through it. It could have been much worse, that blackhawk is like a brick outhouse!