The point is to keep the cursor "in context" as the Scintilla docs say. I indeed never actually wished I had that, but OTOH I do from time to time scroll a little further to see where I'm at, and go back to the line I actually want after I saw. If I had this and was accustomed to it, I wouldn't have to do that.
So I don't care so much, but I understand why the feature can be useful.