The value of Facebook would plunge to a fraction if that was possible. If you, before every click, had to consider what the "target" would make of your visit. Am I visiting too often? Too rarely? So my girlfriends ex is visiting my profile fairly often, what's up with that?
I don't think your assumption is correct. Most Chinese social networking sites, by default, allow you to see a list of the most recent people who viewed your profile, and the exact time they viewed it at.
It's probably a cultural thing, but still think saying that its value will "drop to a fraction" is a bit apocalyptic, especially if you can disable the feature.
I think he was talking of a scenario where the option to disable it did not exist, in which case I completely agree with him. But if there was an option to turn it off, I think we can all agree that most users would choose to and facebook would probably be saved.
Facebook relies on the user having a positive experience with the site. It aims to smooth social interactions. God knows how many girls I've "stalked" (I dislike this term but that's a different point entirely) and I've used the information I gained from anonymously browsing their profile to chat them up. Call me a creep but us primates like using tools :)
Believe me, most people stalk others. I firmly believe Facebook is where it is today thanks to the privacy that enables us to do so.
The dutch social network Hyves introduced this a few years ago, and set it on by default. They got a LOT of comments over this (which they handled quite well: sending around flowers and all). But within a day it reverted to off by default. You can still switch it on, so others see your visit's, but I think it's not that common.
Power users (paying) do get some aggregate stats tho (last month, 40 people, of which 54% girls, visited your profile.)
It's only valid for pages built with FBML. So it's good for tabs (sections) but not for the main page itself. The main page is a newsfeed where you just can't put any FBML. So it makes an interesting tool to track subpages but in general it's pretty useless.
Clever idea though.
But then I see this:
http://grownupgeek.com/facebook-forums-whos-been-looking-at-...
Apparently it's against the TOS.