That may well be true, but for any test to be conclusive someone would literally have to take a sample of at least a few thousand dogs, of each breed type, conduct actual pressure tests, and then publish the bell-shaped curve of the statistic spread to see which "average" is greater. If any.
Without this concrete data, everyone is pretty much discussing opinions and biases, not facts.
Obviously, I agree that the pit bull is (pound-for-pound) the greatest fighting dog on earth ... "on average" ... but lots of them can't bite all that hard.
What makes them such great fighters is their general athleticism and gameness ... and what makes them hang on, even when mutilated, isn't "biting power" so much as tenacity and gameness: the refusal to let go.
Jack