I'd like to add a few things to this.
In my balk against the idea that children shouldn't be buddies, I was thinking really in black and white - such as my examining what friendships means to me.
Of course each relationship with each person that I interact with (called friend) is different.
I discuss different things with different friends. Eric I can discuss everything with, until his eyes get glazed over, and he's just nodding automatically; I don't usually do that to others in real conversation!
I would not discuss something with a child that is inappropriate; something adult, or that may frighten or overwhelm him. If it needed to be discussed, then I would find a way to communicate appropriately.
Different friendships mean different things, as each relationship is individual and special.
I don't value one friendship over another, they are all treasured, as the people themselves are invaluable.