1) Have you read the whole thread? Dr. Dave did a wild arm movement--everyone I know who swoops does a tiny wrist movement. A tiny movement of the wrist is enough to deviate the cue tip.
2) The placebo effect does not explain the many students of mine who swoop successfully or the pros who've done so here and there for a century.
I understand what you're saying. The last second quick wrist action causes more sideways tip speed across the surface of the cb when compared to swooping the entire stroke arm. This makes sense to me, and I actual do use wrist action like this on certain shots. I feel like it works better for me on these shots than a straightforward stroke through the cb. But that's me. I feel like I can shoot softer using a little wrist action and get great spin, where as I'd have to shoot a little firmer using a straightforward hit to achieve the same spin.
It makes sense if I look at it like this: When a cb strikes an ob off center the friction between the balls imparts a slight rotational spin to the ob. When a spinning/rotating cb collides with an ob, the sideways motion across the surface of the ob imparts a little more spin/rotation, or spin tranfer or whatever, to the ob, regardless of the fact that the contact time and friction between the balls is very small. Now, if we have a cue tip moving straight through the cb on an off center hit, natural (due to an absorbent tip and plenty of chalk) there is much more friction and much more contact time (when compared to cb to ob collisions), so plenty of spin is applied to the cb. If, in addition to moving forward through the cb, if the tip were also moving sideways across the surface of the cb it seems like it might create more cb spin, but no more than can be generated using a straight stroke with different speed.
The only thing that really matters is results, and results vary depending on one's ability to strike the cb exactly as intended. I believe I can get the same results either way, swoop or no swoop, max english, but it's all relative to the speed I use for each method. As difficult as this game can be for those trying to learn, it's probably not good to deviate from traditional straightforward stroking fundamentals until the player has developed an excellent stroke and can manipulate it at will.