Is there a reason

[Nixxe]

well SE did drop the ball on a lot of very simple fundamentals like this. Maybe because ARR was so rushed, but who knows

Probably not. It's normal, or at least was normal, for friend lists to function like that. WoW, for example, it still works like that if you use the ordinary friend list rather than RID or B.tag and it doesn't even require confirmation from the other person in the first place.