I wouldn't dismiss so quickly that it's impossible for some people to create orders of magnitude more value than others, or for that distribution to change dramatically with time. In farming, for example, increased mechanization has allowed a ~100x increase in per-worker production, and unless literally every other occupation had the same change over the same time period, that should lead to dramatic productivity differences.

The real difficulty is in deciding who "gets credit" for producing a given thing. Is the person driving the tractor really more productive, or is the tractor itself responsible for producing most of the value (return on capital)? Maybe the bank that provided the loan for the tractor is creating value? Without any of those components, the food wouldn't be grown, so there's not an obvious way to divide it into the sum of individual contributions.