When you have a map and no one else does, their map icons still appear. This would not bother me except when they get within maybe 5 chunks of you their icon turns into an image of their head, which is so huge that it blocks out everything around it. This makes it impossible to travel with anyone as you cannot see the direction your own icon is facing. It also makes it extremely difficult to actually find someone if you are looking for them, because a 5-chunk radius is huge and you cannot pinpoint their location.