So if someone hands you a recipe that calls for 3.362 lbs of pilsner, you're going to make the extra effort to change it to 3.4 lbs on paper then take the time to *precisely* measure out 3.4 labs on the scale, when you could have more easily just measured out 3.362 lbs to begin with. Doesn't that smell futile? why bother tweaking numbers for no other reason than your subconscious tells you that nice, simple, even numbers look nice???? You're going to expend the same effort in measuring 3.4 lbs or 3.362 labs when you get right down to it.
As pointed out earlier, while its just as easy to measure 3.362lbs as 3.400lbs, its a darn sight easier to measure 3.4lbs. To put this in context, one kernel of barley is approx 65mg, so with a bit of rounding (horrors!) we get roughly 7000 kernels to the pound.
So, if Im measuring 3.4 lbs and an extra 100 kernels slip off my scoop/out of the bag, Im still good. But if Im measuring 3.36 lbs, those 100 kernels have put me over. If Im measuring 3.362lbs, its even worse, half a dozen kernels can put me over. Now if 6 extra kernels fall onto the scale, are you picking them off, or are you saying, 3.363lbs is close enough?
You've spent a tremendous amount of time trying to argue specifics to help your case...its variable organics, it doesn't matter.... its just base grains, it doesn't matter. Why not just be as *precise* as you are with all the other parts of your brew process???? i.e. measuring dme for starters, measuring hops, measuring specialty grains. Not using a common method or practice is actually more effort.
Because you are not being just as precise with the rest of your process. As has been pointed out, you are not just as precise when measuring water. As homebrewers, we dont even have the means to measure alpha acid concentration of the hops or the sugar content of the grains. Our boil off rates are educated guesswork. So you are being *far* more precise in one area of the process than almost everything else. That precision is going to get lost in errors and approximations introduced elsewhere in the process, so why bother?
O.1 lbs of base gran difference *doesn't* matter... but why bother go to the extra effort to change it?
Because the effort of rounding in my head is far easier than the physical process of slowing my pour to the right scale or adjusting the number of grains to the 10's. It would be even easier if I didnt need to do so when reading the recipe and people only reported the precision that is necessary.