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...
It's just odd that one would not make green tea at anywhere near the right temperature. Green tea is simply not comparable with black; they are fundamentally different. It is as if there were an ISO standard on the quality of fruits and they are "compared" by assessing color (deviation from yellow is a fault, increasing by reflected wavelength difference).
It's not about comparing quality, it's about comparing consistency. Brands want their blends to be consistent from year to year. So every year they might create hundreds or thousands of different combinations of the specific teas they've acquired, until they find one that tastes as similar as possible to the blend they had last year.
Also, green tea is just fine at boiling, if it isn't of poor quality :)
It means something, which in this case means "taste is individual". I prefer to take the advice of my green tea supplier, who tells me to use 75°C water for brewing my tea. Using other advice is up to the user. Not my monkeys, not my circus.
