I've been wondering can't this be done p2p? Didn't we solve most of the technical problems in the late 90s / early 2000s? And then just abandoned that entire way of thinking for some reason?

If many thousands of people care about having a free / private / distributed search engine, wouldn't it make sense for them to donate 1% of their CPU/storage/network to an indexer / db that they they then all benefit from?