If I understand it, the snail mail concept would prevent users signing up today and subsequently slamming/spamming us. I would question the degree to which this has historically been a problem? The bigger issues from my mind all involve participants who have been members for quite some time. Yes, there is the occasional spammer - but spammers are patient and we will deal w them in the same manner, no matter how long it takes them to gain access.
The question is, what do we gain from the perspective of the current objectives? Anonymity is a strong preference to some. I fear we might lose some valuable contributors should we require a physical address for registration.
I believe best efforts are really to handle this at least for now on the honor system as described in the proposal, and busting folks as they are exposed for violations. I'm not digging my heels in here, and I would frankly prefer some legitimate verification process. I just don't see a verification solution that doesn't create as many issues as it addresses.