IFPS has IPNS [1], the name services (the feature most-directly relevant to the Bittorrent enhancement in question).
To date, I'm unaware of an IFPS crawler-and-indexer search engine.
Content discovery is neither a part of HTTP nor the architecture of the web. It's a feature if it's current landscape, built on top of existing non-ideal ALI and brute force (scanning).
Good web search (represented by Google) appeared around 1998, years after the general availability of the web, when the corpus of web pages was already large. Up to this moment, search is powered by ad revenue.
I don't see how IPFS is significantly different in this regard.
Donating resources to a "traditional" scanning search engine is also probably doable. But unlike Web, IPFS lacks intense linking and thus "citation ranking" (PageRank-like). Measuring relevance is harder.
It's basically the reason search engines stopped trusting meta tags on the websites.