This feature will count each wizard in each realm when you open the Realms in the book, And this feature can change to letter or numbers or both like this: "See in Realms Menu: Numbers > Letters > Both"
This would be great to see how many wizards are in each realm.
While I don't really see anything wrong with it, I also don't see any real benefit either. With all the different areas through all the worlds, the overall count of a realm doesn't really matter so much for the player. There might be 1000 people in a "Crowded" realm and no one doing your dungeon and maybe only 100 in a "Perfect" realm but lots running the same thing. The team up kiosk and feature largely take care of this issue. Showing the real numbers by realm might be interesting to see, but I don't see how it would affect or improve gameplay.