I agree with your observation that this Bloomberg writer is a knucklehead. "Number of managers beating the index" is obviously a silly metric since it matter b

I agree with your observation that this Bloomberg writer is a knucklehead. "Number of managers beating the index" is obviously a silly metric since it matter by how much they win and lose, and an ideal random selection of stocks will obviously have the same expected value as the entire market. However, I think you (and the author) are missing a much simpler explanation for why skew is important: for fixed expectation value, variance is intrinsically bad for risk adverse investors. If you want to try and pick winners and losers in the stock market, you will have to become less diversified to do so. Since there are many ways to interconvert between additional expected return and risk (e.g. insurance), inducing an exchange rate between the two, there is a quantifiable cost for active management even when random. In yet other words: the cost of active management does not go to zero in the limit where the manager picks randomly and fees are ignored. Rather, as soon as you start picking you are accruing a cost through reduced diversification; you cannot come out ahead unless the size of your edge compensates for this non-zero cost.