This only works until you try to use it.
So what can the average FB-er do with this information? Not a lot, I would suggest.
These people we only know through "friending" aren't real friends. They never call, they never pop round to see you if you're ill, they never buy you a beer, and would drop you like a hot lump of plutonium if you were ever foolish enough to ask them to inconvenience themselves on your behalf - as you or I would if they asked. (And if they do agree to, that's an even better reason to make sure they never, ever find out where you live.)
As it is, most of these degrees of connectedness go through a proportionally speaking, absolutely tiny number of hyper-connected individuals. People (if they are in fact people) who don't know you exist, apart from being a number among their thousands of followers. So the chances of sending them a message along the lines of "since we've been friends now for 6 months, how about a ....." and getting a meaningful reply are infinitesimally small, to the point of making the whole thing pointless.