Because data science and machine learning are applied statistics, and if you don't understand how it works under the hood (and not necesarily a very deep unders

Because data science and machine learning are applied statistics, and if you don't understand how it works under the hood (and not necesarily a very deep understanding, sometimes just a broad understanding is enough) you will have trouble adjusting things, debugging edge cases, or simply not know why something works and something else doesn't. (edited for slightly better clarity)