To me it’s the fact that if you try to do it in real life (sorting a collection of objects in the real world), you just end up doing merge sort by accident.

It feels like an optimization of merge sort for computers, rather than a different approach.

This is also reflected in the way that it’s usually taught. Normally merge sort is presented first, and quick sort follows from observations about what would happen if you picked different partition points instead of dividing them in half, and how you can reduce the additional space requirements.

Just look at the little video on Wikipedia, it is an absolute mess of elements being thrown around. Chaos.

Real answer: I tutored beginner programming students for a bit and I guess I just thought quicksort didn’t fit in very well.

Mergesort is an elegant and straightforward example of recursion. Heapsort—you can make a priority queue and then if you plop a heap in there, that’s heapsort. I like the story.

With quicksort, it isn’t that complicated or anything but it doesn’t feel like it embodies an idea in the way the other two do. And it is annoying that the real big-O cost of the popular sorting algorithm is n^2, and the bad case is really obvious. I guess there’s value to getting over the hump of “well heuristics are a thing and big-O doesn’t tell you everything” but I still don’t like it.