why don't they build a yahoo answers beta?

There is a Y!Answers Beta. Read this:

Yahoo! Answers beta was launched today, a free service that allows you to ask questions and get answers from real people on any topic. It allows users to ask straightforward questions and receive specific answers based on the collective knowledge and experience of the community.

"Yahoo! Answers builds on Yahoo! Search's vision to help web users find, use, share and expand all human knowledge. Through using Yahoo! Answers, consumers can more easily share their knowledge, personal experiences and opinions with their community to resolve everyday questions not answered by keyword searches. By archiving and categorising users' questions and answers by topic, and making it searchable, users will be able to quickly tap into the repository of rich knowledge from the community. Moreover, users can keep up with the latest questions and answers on their favorite topics on their My Yahoo! page or any other RSS reader."

"With the largest base of Web users, Yahoo! is in a unique position to tap into the vast knowledge and opinions of individuals to benefit the greater group. Yahoo! Answers lets consumers get their questions answered in a personalised way and share their knowledge with other Web users,"said Ofer Shaked, director of engineering at Yahoo! Search.

The Yahoo! Answers community determines the respective reputation of members who deliver the most trusted, valuable and relevant information. Users vote on the best answer to their question and users who are regularly voted as delivering the best answers can build their reputation over time as a trusted source for information on specific topics.