C2, that drill (back to target swinging down with arms as you described) is NOT a bad drill, or swinging procedure.........for the RIGHT person.
In fact it was the MAIN drill that helped Art Sellinger become a long drive champion.
Art and his coach did a 1 hour Golf Academy show on this drill alone.
Art couldnt stop slicing it, big long ballooning drives, and the reason for it was a bad pivot.
You would think a man with his athletic ability could control his shoulders and move them correctly, he COULDNT! He could not attack the ball on the rear inside coordinate, so he started doing this to quit comming over the top.
All that being said he and his coach did i say they would not give this drill to so and so (he started naming pro's and very good ball strikers), he said this drill would help a person that like himself that couldn't attack on plane from the inside.
I remember it so well because it was my first yr golfing, and i sliced so bad i couldnt keep a ball in play even with short irons, and i didnt know why. I tried it and couldnt believe how it helped change my direction. I still didnt know why at the time but it sure gave me hope.
Now after tons of reading and studying, i know why it helped, and i also understand why several on here say its terrible advice, and i will say it can be bad advice, OR it could help some people attack the ball from the insdie better and start to get them to understand swinging on plane.