The problem this solves is:
If you have to add some hexadecimal numbers and you don’t have a calculator and you want to avoid converting to decimal, but you aren’t that good in hex yet. Or maybe you are real brain dead but you need to do some adding. THIS IS ALL TO BE DONE ON PAPER WITH A PENCIL. I think the method of notation is clean enough that you will not easily make a mistake. Or maybe you have a teacher that is making you had in hex for a test?
Here is the PDF: How to add in Hexadecimal without a Calculator or Decimal conversions with a Pencil and Paper.