Personal messages - to whom and how

I was a little surprised that messages in Habré can only be sent to friends, but now I’m used to it.
The topic is not really about that. In the interface of the site I see some illogicality - when I create a new personal message, the list for selecting the addressee suggests friends from the first and second round. But if I’m in the friend’s habracenter from the first circle, the “send him a message” button is displayed; I think it is illogical, perhaps something I do not understand? :)