It's because there is an enormous body of evidence that talent exists. It exists in the form of different levels of cognitive processing, in different levels of hand eye coordination, in, you get the idea. We know this exists. We can voluntarily affect cognitive processing with cocaine or oxygen deprivation, and involuntarily affect it with things like strokes or head damage (some head damage leads to mastery of skills like music, though most usually it is damaging). Any number of tests show that people learn at different rates, rates predicted by cognitive abilities. I've excelled at things I didn't much care about or practice, and lagged on stuff that I put my heart and soul into.
