I agree, but enough people claim to hear a difference that I won't dismiss it out of hand. I haven't had a chance to do any testing on it myself. Either way, it certainly wouldn't be enough for me to waste my money on but audiophiles are strange creatures.
Every article I've dug up on the matter has offered no real justification for why bi-amping might provide any improvement. Most seem to hinge on the use of a crossover to split the amplifiers. One amplifies the high signals and one amplifies the low signals, thereby freeing each to work more effectively on their individual frequency spectrum.
All of my clock and data signal management expertise is focused on frequencies MUCH higher than home audio (1-50GHz...). In that realm, the suggestion of bi-amping would be absurd for the very reasons you mention. However, I haven't really measured the resultant skew from using two amplifiers in order to determine whether or not it would cause a problem. I know it would in my world, but I can't really speak to home audio in this regard.
