Exactly. As long as you get the proper results within reasonable time and memory constraints, why should you care exactly which algorithm is used?
Maybe it's interesting to know what qsort does under the hood? Maybe you don't know what qsort's time and memory constraints are unless you know the underlying algorithim.
Obviously the sorting algorithim you use matters, so this post has some theoretical value.
Certainly it matters, but I'd expect a library implementation to have more research applied to it than I can do on my own.