The question isn't about mathematical rigor. It's about utility and distraction. In much of the world, phone numbers work even if you add extra numbers that ar

The question isn't about mathematical rigor. It's about utility and distraction. In much of the world, phone numbers work even if you add extra numbers that aren't needed. So I could give you my phone number plus 10 extra digits that change nothing. The end result would be the same utility to you (you can contact me) but with an increased cost in recording, memorizing, chance of error. Using lat/lon to an unnecessary level of detail is the same thing. More digits are more chances to make mistakes, more cognitive load.