XFN: rel-contact – I’m against it

I’d like to follow through on my anti-XFN rant with a series of, thankfully, smaller posts on the subject. I’d like to be able to offer some useful discussion as to what indeed can be done for relationship portability on the Web.

For now, though:

XFN defines rel-contact as being applicable to someone whom you “know how to get in touch with”. Since when was knowing how to get in touch with someone on the Web so rare as to need explicit declaration? Does it actually mean “will return my calls”, or “will respond, if half-heartedly and acronymically, when I IM him”? Why might we need it?