That guy who saved my life
I was talking today in a teleconference about how 'friends' aren't really friends, at least not in most social graphs. I'm not much inclined to do a heroic favor for a friend of a friend of a friend. As a result, because it feels icky to say 'no', I don't hang out in the networking sites.
On the other hand, that guy who saved my life once, he can ask for just about anything and not only will I oblige, it will delight me to do so.
Two ends of the spectrum, with lots in between.
I don't think a large volume at the easy end of the spectrum is a replacement for a few at the hard-earned end. Not at all.