I've read in one of previous threads about it that it's for the purpose of comparing different teas accurately. It's not supposed to result in the best possible tea. Instead it's supposed to make the tea's aroma and taste as clear as possible and it's supposed to be used uniformly across different varieties of tea, so that they can be compared accurately without much error margin introduced by the preparation itself. This may be entirely wrong though. After all, it's just something someone wrote on the Internet...