Travis:

The reason I’ve always been given is that it has to do with the alternator. Basically, the better your alternator is supplying power to the battery, the faster your lights will blink. I don’t know how true it is, so don’t quote me.

That's an interesting theory – although you'd think if that were the case, people would say "one way to test if your alternator is dead is to turn on your blinker and see how fast it blinks". For that reason alone I'd be inclined to rule it out. Hmm.