Just want to chime in for other confused people (I grew up on a Midwestern farm and had never heard of the practice of desiccating wheat, so I've been reading a lot about it on the internet today) -- this appears to be a northern latitude practice - every reference I can find to it is from Canada, the UK and North Dakota, so I'm guessing this has to do with growing wheat in a shorter growing season.

So it's not nearly a universal practice, but on the other hand, North Dakota does account for 20% of the US wheat production. (And on the gripping hand, I don't know what wheat distribution in the US looks like; will ND wheat tend to be consumed in a particular region, or will secondary distribution through eg packaged foods tend to distribute it nation-wide?)