How about this for consideration. Assume two identical bikes at the UCI limit and two riders using them, one weighs 130lbs and the other weighs 170lbs. The heavier rider based on weight alone is producing greater stress on the bike components and frame. This factor weakens the bike's ability to perform to the same level that it would perform for the lighter rider assuming an identical power output by both riders. The frame and components are vulnerable to flex based both on weight and force placed against them, in fact many manufacturers place weight limitations on frames and components based on the weight of the riders. The more inherent flex, the greater the possibility for loss of power transfer. If the above premise is true, does it not possibly negate any advantage perceived for the heavier rider? If I am not mistaken I believe certain members of this forum are engineers, and I defer to them for guidance on this issue.
OK, let me explain this better since I didn't to begin with.
Two riders, one weighs 60 kilos, the other 75 kilos. Both riding the same bike ( flex is not an issue, unless they were riding wet noodles). Both putting out the same power to weight ratio. The heavier rider would have the advantage because relative to him his bike has a lower weight, and his weight to the weight of the bike ratio would be greater, with the same work he would go faster then the smaller guy.
Does that make since to you? Cripes man, you sound like you just got out of philosopy 101, talk like a normal person.