I agree with his basic point that friends-of-friends aren't necessarily friends--although you may or may not be interested in something they have to say in the same vein as attending a party. To your broader point, a lot probably depends on how you use Facebook. For me, it is almost exclusively people I've at least met multiple times and real life at a minimum. And, in most cases, people I get together with when I'm in their town and vice versa. Others use Facebook more broadly which makes filtering more difficult given symmetrical following.