Oh yeah, that would work
Its nice to see this code being used in a productive way, but there is a pretty large privacy flaw that this code can easily start to abuse. Instead of tracking social bookmarking sites, it could be used to track sites you wouldn’t want anyone tracking, for example online banking sites, facebook pages, porn sites, and whatever else you want to keep private.
The good news is that it can only find the pages you have visited by asking your browser if you have visited a specific page. So in order for it to grab your entire history, it would have to ask your browser about each web page on the Internet, one by one. The bad news is that someone could pretty easily compile an extensive list of private web pages.
Personally, I say we patch this flaw. Lets stop displaying visited links in purple, unvisited links in blue. In other words, kill off a:visited. This is a pretty bold statement to make, but the security benefit outweighs the usability benefit in this scenario for me personally. It probably does for you too, when was the last time you went to a website and 1) saw the blue/purple links, and 2) thought ‘Oh good, I know which links of this site I’ve clicked and which ones I haven’t'? For me, that would be somewhere around 1999.
So yes, remove the a:visited property.