Is setVisibleItemProperties method over-reaching its use case?

My understanding of the Form setVisibleItemProperties method is that it reorders existing form fields, but to my surprise it goes further: if you have fewer fields in your form than in the setVisibleItemProperties “ordered fields”, the later would create a union of the two, i.e. it copies all the missing ones to your form in a kind of “take it or leave it” manner. Why?

The method should concentrate on just sorting, that is to say, comparing and only reordering fields that intersect or belong to both sets of fields i.e. ‘form fields’ and ‘ordered fields’. If I exclude one or more fields from a form, it is done for a reason except that setVisibleItemProperties wouldn’t let me.

Is this a bug or perhaps overreaching its use case or and undocumented function?