I don't think I'm advocating that in any way, just at a minimum sanely peppering the code with markers. to keep with the quicksort example, a simple single line comment at the top would suffice:
/* standard quicksort on foo before we make our choice below */
Maybe not insanity, but I would find it a little noisy reading that code, like having to code at a desk near the receptionist.
I wouldn't mind if the comment said "using qucksort because n is expected to be large". But only if the choice of quicksort over some other algorithm was deemed significant.
My point is really to just define the block as containing quicksort when the function it's in does other things as well. Refactoring it into it's own function with a useful name would be just as (or probably more) useful. It's really that lack of either which I see as insufficient
/* standard quicksort on foo before we make our choice below */
That hardly seems like insanity to me.