> Indexing is expensive. If there's a shared public index, that'd make it a lot easier for people to try new ranking algorithms. Maybe the index can be built into the way the new internet works, like DNS or routing, so the cost is shared.

But what are you storing in your index? The content that is considered in your ranking will vary wildly by your ranking methods. (example - early indexes cared only for the presence of words. Then we started to care about the count of words, then the relationships between words and the context. Then about figuring out if the site was scammy, or slow.

The only way to store an index of all content (to cover all the options) is to...store the internet.

I'm not trying to be negative - I feel very poorly served by the rankings that are out there, as I feel on 99% of issues I'm on the longtail rather than what they target. But I can't see how a "shared index" would be practical for all the kinds of ranking algorithms both present and future.