Search needs to be under-sensitive to return results people want. Often a search isn't for precisely the semantic information in the query, but for information

Search needs to be under-sensitive to return results people want. Often a search isn't for precisely the semantic information in the query, but for information generally about that topic (not to mention how queries are often not actually sentences, e.g. if I want to find a white bird with big wings that was eating a fish I might search "white bird wings fish". Maybe that's a bad example, I can't think of a better one off the top of my head but the point stands.)