Going Powerglide

Hey, guys, I am not a racer. I have a question I hope one of you can answer. Why is there such a following for Powerglides in racing. I would think that a well-built Torqueflite, or some other 3-4 speed automatic, would be preferable over a 2 speed Powerglide. Are they that much stronger than a well-built Torqueflite? Again, I don't know much about racing. Please school me.
Thanks,
Mike.