I really dislike this being a rule, but I'd be totally fine with a guideline.
As with many things in mapping, there are cases in which this is useful and in which it is not.
If the mapper is experienced enough to use these kinds of hitsounds to actually enhance or improve the map/feel, then I dont see why this should be forbidden. Ofcourse, if these are used in a way that doesnt make any sense, then we could refer to the guideline and work on that issue.
As with many things in mapping, there are cases in which this is useful and in which it is not.
If the mapper is experienced enough to use these kinds of hitsounds to actually enhance or improve the map/feel, then I dont see why this should be forbidden. Ofcourse, if these are used in a way that doesnt make any sense, then we could refer to the guideline and work on that issue.