Such debate over swivels. I doubt it matters either way. I use them for convenience; a snap swivel allows for rapid switching to different sizes, weights, colors to best match conditions without having to snip line and retie.
ChezJfrey's hardware thoughts:
Swivels don't affect the 'action' any more than what the mish-mash currents and banging into rocks imposes.
Spinner blades don't even need to turn over to be effective.
Spoons don't even need to thump or have line tension to be effective...same goes for spinners
Spoons can even spin in the current as long as the water is cold, or if warmer, they are muted enough to not spook the fish...same with spinners.
I fish spoons and spinners nearly identically, with periodic slack line throughout the drift. A spinner blade might not spin, but as long as the movement through the water causes the blades to change their reflection to the fish's eye, it will grab their attention and the water current does that naturally. In fact, the more subtle and slow the action, the better as it attracts more fish and is less likely to spook them. Spinning or violent action can turn them away, if overdone...that can be mitigated if the water is very cold, or the lure is small or dark.
I caught a steelhead just yesterday, in the glaring afternoon sun with a spoon that was left hanging at the end of the swing, spinning violently in a strong current, but since it was painted black, didn't spook the fish and rather, got a feisty grab.
My lifetime spinner/spoon steelhead stat: 71% of the steelhead I've hooked were on a spinner/spoon.