Overheard: Why do we need Search Wikia?

Search Wikia’s primary innovation will be to tie a user’s social network – that is, information about the user and their friends – into search results. The idea is that a user and their friends share a common set of preferences and that using that information makes search results more personalized as well as more relevant. Saumil Mehta, Search Wikia launches: Will it threaten Google?

Saumil wrote earlier: We’ve tested Grub, the service’s way of crawling the Internet’s web sites to collect data. Grub is a “distributed search crawler,” so named because it lets people download a software to do the crawling from their own computers, thereby letting thousands of people contribute to the process. It is intuitive and easy to use. However, large questions remain about the ability of Search Wikia’s approach to scale to the entire Web.

I spent some time last night poking around Search Wikia. I’ve read a lot of articles. Saumil did a good job of connecting the dots about how it’s supposed to work — but I still don’t see why we need it. Can someone explain what I’m missing? The part I really don’t understand is why they’re asking visitors to contribute a mini-article or definition for the search results page when they could just pull in the first paragraph from a Wikipedia entry.