The trouble is that this centres the fan chart on the mode of the distribution (the single likeliest outcome), and not necessarily on the median (the value that divides the outcomes, ranked by size, exactly in two) or the mean (the sum of the outcomes divided by the number of outcomes).

ECONOMIST: A la mode | The

This procedure centres the chart on the median, not the mode (if the two are different).

ECONOMIST: A la mode | The

Mr. SILVIO PIETROLUONGO (Chart Manager, Billboard Magazine): Back when 45 singles were the mode of purchasing choice, record labels really released one song physically, you know, every few months.

NPR: On Billboard Chart, No Longer Lonely At Top