Comment by HelloNurse

> Second, sorting is a solved problem. Regardless of theoretical efficiency, we have so many ways to sort things, there is almost always really fast in practice ways of sorting data.

By the same reasoning, economy would be a solved problem: you just need to have money.

Computing correlation by sorting a large amount of samples instead of reading them once is a cost difference that can make your data processing practically infeasible despite the efficiency of sorting algorithms.