I'd say 2 good reasons for this system, Cost and aircraft availablilty.
A dedicated winch ship would be nice, but expensive.
It's a vast area that Parks Canada covers. This system can be installed on any aircraft. It's hard mounted on the ships that have the proper mounts bolted on, or attached via a belly-band on those who don't.
You are correct, travelling in bad Wx with a long line is difficult, but Slinging with live bodies is kept to the minimum distance required. They truly frown upon being dragged through the trees !