I agree that gram measure is going to be accurate. Because you're doing it yourself. What I am questioning is whether a manufacturer isn't scrupulous about measuring out what product is produced... it's in the manufacturer's interest to make it as accurate as possible, because of the cost of ingredients.
I remember my Weight Watchers leader's comment that if a database says x calories and the box says y calories, go by the y calories. The manufacturer has more rules to go by and standards to meet and economic incentives to get the ingredients exact.
But if it helps a dieter to measure and recalculate, then by all means, measure and recalculate!