As I said Wouter, this is the "IDEAL attitude" which is a bit like taking the results from "ideal" tank testing of a hull and expecting it to perform to those exact standards "out on the water" with no compromise for water, wave, wind, etc effects on that hull.
Sailing is, if nothing else, a compromise at all times between the "theoretical ideal" and the practical application of balancing the ideal with the "real", never the less, when positioning the crew weight, trimming the sails, etc, the "ideal sailing attitude" of the boat has to be always foremost in the awareness of the sailor if he/she is to achieve the best possible performance out of their boat.