Money is absolutely part of the formulation of relevance. It's just not the whole equation. Nor is word-matching (altavista), nor is popularity (google). But each is relevant.

Someone (advertiser) is paying money because they believe they have information relevant to you. How is that categorically different than the blogger/webmaster who's paying money (time/hosting) because they believe they have information relevant to you?

All information has a cost associated with it. And that cost bears some significance on the value of the information. Measuring and weighing that significance relative to other inputs is the beauty of an effective system.