Both thicker gauge and higher tension usually give lower power. Lower power necessitates a faster stroke. A faster stroke imparts more spin, maybe.
Don't forget the human element.
This is very true. So the real question is whether or not, all else being equal, would a thicker main enhance spin potential.
The corollary to your point is that a faster stroke requires better timing to maintain consistency and precision.
The optimum solution is a string bed that enhances spin within the limits of the user's abilities.
So are 17 and 18 cheater's gauges? Did we already know that? Or, to validate this querry, would the 15L and 16 gauges be the cheater strings? Do we shoot for a happy medium, will we have to figure out what we like that also works with our swing speed/timing ability? This extra info about strings might motivate us, the string buying public, to give it some more thought. I always thought the only reason to go from 16g to 17g was for my closed string patterns.
Also, is a fat gauge spinnier for a gifted/advanced/pro player with a fast swing and impeccable timing? Would these people get less spin out of a narrower gauge, given that they wouldn't break it? Is the fat gauge really spinnier, or just more durable? Would these people get sufficient spin from any type of string, as long as it wouldn't break?
To be quite honest, I don't think increasing gauge, IAOI, will increase spin potential. If it does, it's a distant worry behind durability.