jmccormac - 8:28 am on Aug 16, 2012 (gmt 0)
That's a whole new debate but the central reasons why they never took off were simple. The operators failed to monetise them sufficiently to cover costs and the operators were unable to deal with junk and spam in the SERPs.
Cooperation-based, open-source search engines that were done with non-commercial interests have been around for some time, but none that I would know of took off. Perhaps a good bridge to the opening statement of this thread.