@anildash Why do you think it's a solvable problem?
Once a search engine catches on, the reward for gaming it becomes functionally infinite.
(There's the AWS line about any online service is really just a distributed denial of service attack you asked for, too. The minimum resources required are not small.)
What we're seeing is an unstable system that pushes any successful search engine -- meaning it works well enough that people use it -- from "cooperate" to "defect" because it is used.
@anildash If you want a stable system, you have to build something where "defect" isn't an option.
There's no way to do that with a global distributed system that's free at the point of use.
You can conceivably have a pay-to-use index, but that's going to start involving a quality measure and algorithmic quality measures aren't available. (The proxies are what gets gamed.)