[vannevar]

If distribution cost were high and creation cost insignificant, copyright would not be needed -- the creator can handle competition from other distributors...

While this is probably true, it certainly doesn't mean that distributors want such competition. They want a competitive advantage, and it's much cheaper to get such an advantage by picking popular authors than having a technological arms race or price war with other distributors. Copyright was introduced to provide an artificial monopoly for distributors.