Why is that?
Are you saying that if I took a big five-channel amp like
this, and used four of the channels to bi-amp my mains, and the other for the center, it wouldn't be considered bi-amping?
I don't see that having a single power supply is the limiting factor, though it can be. If the power supply section of the amplifier is built properly, but the amp sections are poor, then it's a limitation of the amplifier sections.
I agree that using potentially reassignable channels 6 and 7 of a receiver probably won't get you much more. However, if that receiver's power supply and amps are properly designed, you might.
I'm not trying to cause any trouble, but it's a fairly bold statement you're making.