I'm not certain what you mean by human factors, so correct me if I've misinterpreted.

If by human factors you mean basic heuristics based on human intuition, that fails too. It might satisfy 50% of viewers but there's too much diversity in taste for this to be a good model.

I'm not defending the metric as described, but there's obviously good data driven approaches and bad ones. The trick is to find a solid proxy for the business problem and to try to weed out any dark side effects by applying it.