Actually, I don't see logical reason why such rule should exist. If we start with a premise that the sport of cycling wishes to determine its winners purely based on sporting effort, then the rules of sport should try to avoid that other factors have effect on the result - in particular crashes, punctures, and other mechanicals. By allowing that a rider is able to minimise negative effect of such a misfortune by accepting mechanical help from a rider of another team, the goal of reducing effect of non-sporting factors would be achieved, wouldn't it?
And for those who claim that the rule is meant to prevent instances that Clarke helps Porte, but would not help Contador in the same situation, which means Porte has unfair advantage - well, is this really such a significant unfairness that it outweights the benefit such help brings in order to determine winner mainly based on sporting effort as described above? When you think of it, there is multitude of other situations which also create more favourable treatment to some riders compared to others - e.g. Porte may puncture the next day and have neutral support car right behind him vs. Contador punctures the day after and has to wait minutes for support car.
What I mean is that the sport is normally trying to minimise effect of incidents on the result by neutral support, by team cars following riders, so why do they have reason to prohibit another method of assistance that is other team rider's help? Especially if, as many have noted, it creates such a great example of sportmanship.
And for those who claim that the rule is meant to prevent instances that Clarke helps Porte, but would not help Contador in the same situation, which means Porte has unfair advantage - well, is this really such a significant unfairness that it outweights the benefit such help brings in order to determine winner mainly based on sporting effort as described above? When you think of it, there is multitude of other situations which also create more favourable treatment to some riders compared to others - e.g. Porte may puncture the next day and have neutral support car right behind him vs. Contador punctures the day after and has to wait minutes for support car.
What I mean is that the sport is normally trying to minimise effect of incidents on the result by neutral support, by team cars following riders, so why do they have reason to prohibit another method of assistance that is other team rider's help? Especially if, as many have noted, it creates such a great example of sportmanship.