I learned and use it because of the want to get into overhanging rock formations on the lake I live near. When I am about 3-4 feet from the "cave walls" the lake bottom can be a jumble of rocks and a sculling draw is hard to do because the paddle can hit at the top (overhang) more, and also the blade in the water hits more often because of the sloping rocks coming up to meet the water line. But by pushing myself into those pockets I can avoid much of the interference with the paddle.
I was showing it to 6 kids from our church yesterday and I didn't know what to call it.
Most times the sculling draw is easy to do, but along the cliff walls and in the overhanging "caves" the sculling pry (now I know what to call it) works a lot easier. I never thought it would be hard to do and I had to work on it some, but it came pretty easily. It has only the application I mentioned above (so far for me,) but for that use it's great, and I had the kids doing it (albeit a bit coarsely) in only about 30 minutes.