For the most part it’s best to use system provided sorting implementations, but somebody has to write those implementations, so every once in a while somebody needs to do it (in practice by looking up a reference implementation of course).
But also it’s good to understand things like big O scaling and why we use quicksort rather than a naive insertion sort and when to use quick sort vs merge sort or some other form of stable sort.
Name an anime without a shower/bath scene. It’s a lot harder than you’d think.