I was just wondering why Yahoo had to have another search engine, AllTheWeb? Though it has PR 8, how does it help Yahoo Search Engine?
Yahoo bought AlltheWeb and AltaVista back in the day when they were competitors. They used all the best from each engine in Yahoo and left the old engines out there using Yahoo's database. I guess the reason they leave them alone is because they still drive a small amount of traffic and provide additional places to display paid search ads and paid inclusion feeds.
Yeah each search engine may still have a small following. So it wouldn't make sense for Yahoo to just redirect the traffic or close down either search engine. They don't want to risk losing those loyal visitors. It's still a source for income through submissions as well as advertising space. For their advertising network to thrive, they need to provide as much ad space as possible.