Why does everyone ask about"show names" for their horses?

It is bugging me that I see all these things on here for "show names" for peoples horses. And they aren't usually for like foals either they are for older horses.Do people not realize that us people who show don't make up "show names" that "show names" are the registered names of our horses and you don't get to just make it up unless you are the one to register the horse? Could someone please explain why people do this?