Maybe I came into this too late, but I'm confused. If this is the case, I do not understand the mashing process. Am I to suppose that my beer lacks body if I don't boil the grain or that I can't get proper conversion without mashing above 169F ? Step mashing does improve conversion efficiency, but the amylase enzyme denatures above 168F.
It didn't take much effort to find this on the web:
Barley starch is a mixture of amylose and amylopectin. The percentage of each component can vary and the length of amylose helices and the size of amylopectin molecules can also vary between different varieties of barley. And, as we’ve seen, starch is packaged into granules, and is associated with varying levels of proteins and lipids. As such, there is no one temperature that could be given as the gelatinization temperature for barley starch. Barley starch from malted barley typically gelatinizes in the 138–145 °F (59–63 °C) range, but various studies have documented temperatures from 126–154 °F (52–68 °C).
When starch granules are exposed to hot water, the amorphous regions (composed of mostly amylopectin) begin to swell first. As the starch molecules begin to dissolve and are “opened up,” water molecules progressively become associated with the hydroxyl groups (—OH) on the outside of the molecule. This swelling disrupts the layered structure of the granules.
Smaller granules — which typically have higher amylose levels and more protein on their exterior — gelatinize at slightly higher temperatures than the more amylopectin-rich large granules. (And remember, most of the weight of the starch comes from large granules.)
Older studies have shown different patterns of gelatinization (with regards to how quickly large and small granules dissolve) in different barley varieties.
If you’re looking to brew a dry beer, an initial rest in the 140–145 °F (60–63 °C) will help, but the starch may not be fully gelatinized at that temperature, so a “finishing” rest in the 148–152 °F (64–57 °C) should be employed to finish the mash. (If you want to be doubly sure, employing a mash out — raising the grain bed temperature to around 168 °F (76 °C) — would also be a good idea.)
To me this, contradicts what you posted, unless I misunderstand. I have been brewing for a while and with great success. My beers don't lack body and my conversion efficiency is between 85-90%, sometimes as high as 95%. What am I missing or doing wrong?
. People have been making beer for thousands of years no need to get into a tuglewar about who's brewing method is best as long as it's decent drinkable beer that's the main thing 
