Because with a group of 12, that would get messy really fast.
Like GW2, each group member is a dot on the map (and on the edge of the mini-map) and trying to find the person who says "The bounty is by me" requires hovering over a number of different dots to find the right one to move to.
If you look at the map, they show up as carrots. They probably do on the mini-map as well, if you use that addon.
You can also see the carrots on your screen if you are relatively close to a group member. You might be able to adjust that in the settings.