Laura and George, you're both missing the point.
The anchovy is not there as a major player in the dressing. If you didn't know it was there, you would never think "Aha, there's anchovy in this dressing!" It is a background player, something that makes everything else taste great.
This could be an example of umami, that ineffable taste that has been getting all kinds of attention lately in the cooking world. It's something found in soy sauce, mushrooms, tomatoes, Parmesan cheese, and a lot of other odd places. It gives food a feeling of being something "more", of having a fullness and yumminess. And it's absolutely terrible when over-used, or tasted on it's own, because the main chemical component is MSG.
But it works in small amounts, as something in the background.
Jose might have something more to say about this.
I know Jeffrey Steingarten wrote an entire article about MSG, because it's in that book I'm reading. He wondered why, if MSG is supposed to cause so many headaches from people eating Chinese food, why doesn't the entire country of China suffer from continual headaches?
Personally, I'm not attracted to adding MSG in it's chemical form to the food I serve to der Brucer. But I do like to use the natural sources where it is found as ingredients in my cooking.
BTW, all those Doritos and potato chips that come in flavors like BBQ and Sour Cream and Chive and Super Cheesey and on and on and on...
Guess what! They're loaded with MSG. Check the ingredient lists on those bags of chips next time you crave a snack.
Give me anchovies, olives, and all those other natural ingredients any time!
(Although, natural-flavored Cheetoes does sound like another oxymoron, doesn't it???!!!)