In Search engine optimization: beyond search keywords, Gerry McGovern makes a key point here that expresses the rhetorical situation of SEO: we should be optimizing for people who search.

Sometimes, those involved in search engine optimization lose sight of certain absolutely critical issues. The objective should not be to optimize for any particular search engine. It is to optimize for people who search. This is a subtle but essential distinction. It's easy to get obsessed with the technical aspects of Google and Yahoo!