Think about it...
Millions of webmasters will be submitting long lists of low-quality or spammy sites, which Google can then use in its algorithm to penalize not only the sites that are providing these poor quality links, but also those that are linked to by these sites.
This spells disaster for any site that makes it too easy to get a link back to your site. For example, popular "easy" sources of links have traditionally been:
- Blog comments
- Forums
- Web 2.0 sites
- Article Directories
- Web Site Directories
- Poor quality, automated Blog Networks with no human-approval "citation" process
- Social Bookmarking Accounts
The "low hanging fruit" sites that promiscuously give out too many links, too easily will most likely see poor pages (or even their entire domain) get penalized.
But what's worse is that a penalized domain may also penalize any other sites that it links out to. (Think of the opposite of PageRank - where poisoned "link-juice" flows through to sites that are linked from them.)
Now, much of what I've mentioned is speculation at this point, but with this additional data, Google is free to incorporate these kinds of "tweaks" into its ranking algorithm. This is data that they've never had at this kind of scale, ever before.
It makes sense, doesn't it? If Google identified a website as being ripe for link-exploitation, and a lot of websites are using it to build easy links, then it may infer that anyone also using that site for links is a candidate for penalty.
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